Download Food, Energy, - Project 2061

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Food, Energy,
Growth
and
Michigan
Dept. of Education
New Directions teaching materials have been created tc help teachers
develop scientific literacy and conceptual understanding for all of their
students. As companions to the new Michigan Essential Goals and Objectives
for K-12 Science Education, they illustrate the ideas about teaching, learning
and curriculum that underlie the new objectives.
Food, Energy, and growth is an 8th, 9th, and 10th grade unit designed to
help students construct a clear understanding of the ways that food is used by
our bodies for energy and for the materials needed for growth and repair. It
has also been designed to help students learn to pose questions, search for
solutions to problems, work together with others, and value the need for
evidence in making decisions.
Philosophy
and
Rationale
Specifically, it illustrates the four important goals for science education listed
in the Introduction and Rationale of the new state science objectives:
1) Scientific and for all students.
Scientific literacy includes the ability to use scientific ideas to understand the
world around us, to construct new ideas by asking questions and searching
for answers, and to reflect on the adequacy of explanations and solutions. In
this unit, students learn how to use the scientific ideas of cellular respiration
and protein synthesis to explain how the energy needed for life activities and
the materials needed for making new cells come from food, and they use the
scientific ideas of structure and function to explain how the digestive and
circulatory systems work together to provide the cells with what they need. As
they do this, they sharpen their abilities to ask questions and construct
answers, and reflect on the evidence needed to support arguments and
decisions.
Scientific literacy is not just for those who show an early interest in science or
those who might pursue related careers. It is for all students. Because fewer
and fewer young women and minority students develop an interest in science
and technology, these New Directions units incorporate materials and
approaches to support and encourage them in succeeding and staying in
science.
2) Understanding over content coverage.
To be scientifically literate, students need to have a deep and connected
understanding of “the big ideas” of science. In this unit, those ideas include
1) that human digestive systems break down the components in food into
several basic parts, some of which are building blocks of new cells, others are
sources of energy; 2) that life activities occur in cells, and that those activities
are primarily chemical in nature; 3) that human nutrition depends on eating
correct proportions of food components; and 4) that various cultures have
developed diverse diets, all of which provide the energy and materials that all
people need.
This kind of conceptual understanding takes time. That’s why these units are
relatively long. For some teachers, the commitment of 6 to 8 weeks for one unit
in science seems like a sacrifice of other important content. But to really
understand the“big ideas,” students need to see how theoretical concepts, like
“cellular respiration” and “protein synthesis” connect to the real world of
Food, Energy and Growth
TEACHER’S
GUIDE
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people eating--the fats, carbohydrates, and proteins in our food, our needs for
energy and how they change during exercise, and what happens when we gain
and lose weight. And they need to see how the concepts they learn make sense
to them in terms of ideas they’re already familiar with, whether they have to
do with agriculture or with chemistry. This kind of learning is fundamentally
different from science teaching that skims across many topics, often
overwhelming students with technical vocabulary. It is especially important
for developing scientific literacy in all students.
3) Learning that is useful and relevant outside of school.
Scientific literacy means an understanding of science that can be put to good
use outside of school. For that reason, we have chosen topics for the New
Directions teaching materials that connect scientific ideas, skills, and habits
of mind with important “real-world” systems, events, and problems.
But research continues to show that students bring to the classroom theories
about how the world works that are sometimes at odds with scientific
explanations. In this unit, for example, students often believe, naively, that
the oxygen they breathe simply enters the lungs and is somehow transformed
into carbon dioxide, without recognizing that oxygen is needed in the cells to
chemically extract energy from the food they eat. One of the important goals
of these new materials is to connect students’ developing scientific ideas with
the ideas they already use to make sense out of the world. Sometimes this
involves relatively little change; sometimes it involves “mind-bending” change.
4) Interdisciplinary teaching.
The world is interdisciplinary. Botany alone, or physics alone, or economics
alone, doesn’t provide answers to important social questions. And students
shouldn’t see the world as compartmentalized, with language arts occurring
between 9 a.m. and 10 a.m., mathematics between 10 a.m. and 11 a.m., and
science only after lunch.
These units draw from as many scientific disciplines as necessary to dig deeply
into the topic. In this unit, human physiology, cell biology, chemistry, and
nutrition are closely woven together. The unit also provides multiple
opportunities for using and strengthening students’ expressive and quantitative
abilities.
On the whole, we hope that these units provide new resources to teachers for
improving student achievement in science. The outcome we’re all striving for,
though, is not just better test scores. What we really want are scientifically
literate citizens.
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Michigan Department of Education
About This Unit .....................................................................
vii
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"Cluster by Cluster” ............................................................... VllI
Classroom Environment ........................................................
ix
Table of
Contents
Supporting Young Women and Minority Students .............. ix
State Science Objectives .........................................................
X
List of Materialss .....................................................................
Xiv
Preparing to teach Cluster 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 1
WHY
DO LIVING THINGS NEED FOOD?
(AN INTRODUCTION) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Lesson 1
Food stores energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Lesson 2
What is in various
Lesson 3
Where the action is: The cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Students observe energy released from a burning marshmallow and relate this
to their body’s need for energy.
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Students identify the appropriate test for each of four food components (sugar,
starch, protein and fat) and then use these tests to decide which of these
nutrients are present in various foods. They discuss the need to eat foods that
contain each of these components.
Food, Energy and Growth
After thinking about what cells are and where they can be found, students make
a sand sculpture as an analogy to the cell structure of living things.
TEACHER’S GUIDE
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Preparing to teach Cluster 2 . . . . . . . . . . . . . . . . . . . . . . . . ...*..... blue lab prep 7
HOW DOES FOOD GET TO WHERE IT’S
~ USED? WHAT HAPPENS TO IT
ALONG THE WAY“. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
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Lesson 4
The food trip, part 1: The digestive tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Lesson 5
Digesting foods: Where does it start? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Lesson 6
More on digesting foods: Breahing down proteins . . . . . . . . . . . . . . . . 22
Lesson 7
Getting food to the cells:
Moving through tight places . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Students show what they know about the path of food in the human body by
drawing the organs involved in this process on an outline of the human body and
writing about it.
Students either design an experiment or use the given instructions (testing
oatmeal before and after it has been chewed for sugar) to explore the part of
digestion that occurs in the mouth.
Students use meat tenderizer and pineapple as a source of enzymes to digest the
protein present in gelatin. They relate this to the actual digestion of protein in
the body.
Students use window screen with 1) sand and gravel and 2) gelatin and enzymes
as a simplified model of digested food particles moving into the blood stream.
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Lesson 8
The food trip, part 2:
Taking a ride on the blood bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Students make a model of the small intestine, blood vessels, and cells, and use
pictures of food particles to simulate digestion, movement of these particles into
the blood vessels, and transport of digested food to the cells.
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Lesson 9
The digestive and circulatory systems:
Putting it all together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Students complete the picture they made at the beginning of the cluster and
write a story about the food trip as a way of solidifying what they learned in this
cluster.
Preparing to teach Cluster 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 13
HOW AND WHERE IS FOOD USED
IN HUMAN BODIES’,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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Lesson 10
Breathing and exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Students discover what products are formed as the body uses energy and how
they change with exercise.
Michigan Department of Education
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Lesson 11
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How your body actually gets energy from food
Lesson 12
Growing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lesson 13
Weight gain and weight loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Students make and observe a burning butter candle. They compare the
reactants and products of this energy-releasing process to the same process in
their own body. They consider the chemical processes occurring in cells.
45
Students go back to the model of the digestive system they made in Cluster 2 and
use the amino acids from digested foods to synthesize new protein. They make
different arrangements of various numbers of amino acids to simulate the
synthesis of different proteins, and discuss how organisms grow by adding new
proteins to cell structures, resulting in cell division.
Students analyze several hypothetical cases of weight gain and weight loss and
decide what factors caused each effect. They make predictions for specific
situations and develop plans by which they can attain their own weight goals.
They chart a hypothetical person’s weight throughtout the day as materials
enter and leave the body.
Preparing to teach Cluster 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 15
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DO WE GET WHAT WE NEED FROM
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WHAT WE EAT’,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
Lesson 14
Diet and nutrition: What do you eat ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Lesson 15
Diet and nutrition= What do others eat .? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Students explore the nutrition information on food labeling, categorizing various
foods by their proportions of carbohydrates, fats, and proteins. They compare
this information with the “Eating Right Pyramid,” and then analyze the eating
habits of a fictitious character as well as their own.
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Students consider and analyze healthful diets of vegetarians, and of other
cultures that use less meat for their protein source.
Appendices
A.
Unit content summary and student misconceptions
B.
Unit assessment
C.
Black line masters for student hand-outs and overhead transparencies
Food, Energy and Growth
TEACHER’S GUIDE
V
Scientific
Literacy
Scientific literacy is an understanding of the world around us
that provides insights into how things work and why things
happen.
Scientifically literate people:
are familiar with the natural world and respectful of its
diversity and unity
are skillful in constructing new personal knowledge through
asking questions, gathering information, and thinking critically
know key concepts and theories of science
can describe, explain, predict and design systems, events or
phenomena in the world around them using scientific
knowledge
are empowered by scientific knowledge and ways of thinking
for personal and social awareness, problem-solving, and
decision-making
understand the nature of science and technology, recognizing
their strengths and limitations
recognize historical and cultural factors that shape science
and technology
continue learning throughout their lives, using scientific
knowledge and ways of thinking.
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Michigan Department of Education
“.
Why are people becoming more “health-conscious” these days?
Why are many trying to watch what they eat? Is it unhealthy to
skip a meal and eat chips and pop instead? Why shouldn’t we eat
pizza every night? What should we eat to be healthy?
Why do people-and all living things-need food? How and
where is it used in our bodies? How do the internal systems and
organs in a human body work together to get what we need out
of food?
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About this
Unit
These are especially important questions because our well-being
depends on making smart decisions about the foods we eat and
other healthful activities we engage in, including exercise. We
need to be able to listen critically to the claims we hear all around
us about food and healthful behaviors, to analyze those claims in
terms of their scientific merit, to find additional information
when necessary, and then to make smart decisions.
To make those decisions, students need to use scientificknowledge,
in this case from both biology and chemistry. This knowledge
includes the processes that occur in the digestive system of
breaking down food into its constituent parts, the movement of
food and oxygen through the body to all cells, and the use of food
and oxygen in the cells for supplying energy and for building new
materials that become part of our bodies when we grow.
But being smart about food decisions requires more than
knowledge about digestion and cellular respiration: Equally
important, it requires certain skills and habits of mind-the
ability to pose questions, to find necessary information, to set up
tests; the disposition to demand evidence and logical reasoning
in support of assertions, and to think critically about others’
claims; and the willingness to consider other ways of acting
(other ways of eating, in this case) as reasonable and appropriate
solutions to particular social or cultural conditions. This unit
will help students develop this specific knowledge, and more
general skills and habits of mind.
Food, Energy and Growth
TEACHER’S GUIDE
vii
Cluster
By
Cluster
This unit is composed of four clusters, each building together a comprehensive
story of the use of food and energy in humane--one of the key questions
in the Framework of the new Michigan Essenfiral Go& and Objectives for&
12 Science Education. As a unit, these materials attempt to put the goals for
Michigan science education into practice (see page 1, Philosophy and Rationale.)
This is how the unit works:
To develop a broadly-connected understanding of how organisms use food,
this unit brings together cell-level, system-level, organism-level and
community-level considerations about how food releases energy and provides
materials for growth and repair. It cuts across traditional topics of human
body systems, cell processes, and diet and nutrition, focusing primarily on life
science issues but also dealing with bio-chemistry. To connect scientific
theory to everyday life, these ideas are embedded in the important questions
of what people need to eat to maintain their health-not only in middle class
communities across the United States, but in diverse cultures both in the U.S.
and in other parts of the world.
Cluster 1 is an introduction to the unit. Its intention is to open up questions
having to do with diet, growth, and energy; to provide an overview of why
people need food; to establish the three major components of food
(carbohydrates, proteins, and fats), and-although this is not a unit on cell
specialization or cell reproduction-to locate where energy is actually extracted
from food and where growth actually occurs: in cells. The first cluster does
not present in detail the processes of extracting energy or using materialsthese are presented in Cluster 3, after Cluster 2 talks about the digestive and
circulatory systems.
Cluster 2 is about how the digestive and circulatory systems work together
to distribute food components to the cells. Students trace a piece of food from
when it enters the mouth until it reaches the cells, describinghowit is changed
from plant or animal materials into essential substances that cells can use
(simple sugars, amino acids, and fatty acids); how these substances pass
through the digestive system into the circulatory system; and how they are
distributed throughout the body.
Cluster 3 takes a submicroscopic look at what goes on in cells, and relates
the processes of cellular respiration and protein synthesis to human activities
of energy use and growth. By the end of Cluster 3, students should be able to
explain in detail the chemical process that occurs when cells extract energy
from food, as well as the ways cells use materials from food for growth and
repair of our bodies.
Cluster 4 “puts it all together,” giving students opportunities to look carefully
at what they eat and analyze whether their diets provide adequate nutrition
for energy and growth. Students also look at what people in other cultures eat,
and develop an appreciation for the healthy diets that other cultures have
devised that rely much less on meat for protein.
Cluster 4 is optional. Clusters 1 through 3 together provide good, sound
biology; the material in Cluster 4 is often discussed in health classes. If your
school decides that health class is the only place for diet and nutrition, at least
you can be satisfied that your students will have the necessary biology to
understand the rules they learn for healthful eating!
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Michigan Department of Education
Even though different teachers have different personalities, and different
approaches to helping students learn, what’s common in classrooms where
students are really making sense of science is studcnt activity -students
working, students thinking, students explaining. “Hands-on, minds-on”
means that doing and thinking are linked together in developing scientific
literacy.
Classroom
Environment
Classrooms where students are really making sense of science and learning
to use its key ideas and habits of mind in their daily lives have a culture where
students are continually trying things out, discussing their ideas, debating
solutions to problems, being critical as well as open-minded, listening and
thinking. Whether they are learning how to explain why something works, or
how to describe a natural system in detail and show the connections of its
parts, or how to use information to make predictions, or how to design and
build a tool or a system, students have to be allowed to try out their ideas and
explain their reasoning.
And teachers have to value students’ thinking, both for the insight it provides
to further a student’s development, and because it is the product of the
student’s honest efforts to grapple with the important questions being raised
in the class. In this environment of working, thinking, and listening to others,
students learn that their ideas are important and valued, and that science is
not authoritarian, dogmatic, and esoteric.
Unfortunately, there are far more white males in scientific and engineering
enterprises than women and members of minority groups, including African
Americans, Hispanics, and American Indians. We say “unfortunately" because
the contributions of women and minority persons to the scientific and
engineering enterprises has historically been strong, even though they have Young Women
been underrepresented by numbers.
Supporting
Clearly science and technology are fields that many persons can make strong
contributions to, and that all persons should have the opportunity to choose.
Many of our educational practices have pushed women and minority students
away from science, though.
and Minority
Students in
Science
These materials, coupled with the best intentions of Michigan’s teachers, are
attempting to provide support and encouragement for all students to take
more science and mathematics courses and consider scientific and technical
fields. Theyaredoingthis byintegratingculturally-relevant sciencematerials,
reflecting the perspectives, experiences, events and interests of different
ethnic groups relative to their roles in the scientific enterprise, into these
teaching units. These culturally-relevant materials emphasize the social
impact that all groups, including women, have had on mankind, and the
significant consequences and implications for scientific improvement and
achievement.
We do this for several reasons. Integrated culturally-relevant examples will
promote student pride in their ethnic, cultural and gender heritage, as well as
provide an understanding and appreciation of how their culture influences
the nature and structure of science. Also, all students need multicultural
science education, even if they live in entirely white communities, in order to
appreciate the full spectrum of ethnic diversity that exists in our society, in
preparation for the day when they will most likely work along side someone
of a different physical appearance and cultural background.
Food, Energy and Growth
TEACHER’S GUIDE
ix
State
Objectives
for this Unit
Specific objectives for this unit, from New Directions for Science Education
in Michigan: Essential Goals and Objectives are listed below, along with
specific unit learning outcomes derived from each objective.
The Constructing Scientific Knowledge and Reflecting on Scientific
Knowledge objectives are integral parts of each New Directional. . Each
Constructing objective and each Reflecting objective is woven throughout
each unit, tied closely together with Using Scientific Knowledge objectives.
Constructing
Scientific
Knowledge
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X
Pose questions about the composition and nutritional value of familiar
foods and daily diets.
Suggest appropriate tests for determining the composition of familiar
foods, and design and conduct them.
Use sources of information about the nutritional composition of foods
(including food labeling) to analyze and make decisions about diets.
Michigan Department of F.&cation
Reflecting on
Scientific
Knowledge
Justify the nutritional benefit of particular diets, based on evidence
about foods’ composition and reasoning based on knowledge of cellular
respiration and protein synthesis.
Distinguish opinion from fact in claims about the nutritional value of
certain foods.
Articulate personal assumptions about diet and nutrition.
10) Recognize the convibutions
.:
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cultures and
Recognize the nutritional value of diets of other cultures which do not
rely heavily on meat for their major protein source.
Appreciate the ingenuity of other cultures in devising such diets.
Describe contributions of food products from other cultures to typical
U.S. diets.
Food, Energy and Growth
TEACHER’S GUIDE
xi
Using
Scientific
Knowledge
. Explain how food is used by humans for energy.
. Explain how food is used by humans for growth.
. Analyze and describe food as made up of carbohydrates, fats and
proteins.
. Explain why humans need to breathe in oxygen.
. Explain where the carbon dioxide comes from in the air we
breathe out.
. Explain how excess food consumed by adult humans is stored as
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tissue.
Explain the role of minerals in human growth.
Explain how humans gain weight.
Analyze sample diets for proportions of food constituents.
Construct diets beneficial for growth and energy needs.
Objectives 5-7
Related concepts;
terms
.),
and t o o l s ,’ , ,
:. ‘. real-world c o n t e x t s
:.. ,‘,, :,;;jji:j,:,::,:c. .:j::. ““‘/
;
Trace the path that food follows as it moves from the mouth to
the cells.
Describe what happens to food as it travels through the
digestive system, using words and pictures.
Explain how food needs to be digested.
Explain how oxygen reaches the cells.
Explain how components of food reach the cells.
Explain how the by-products of cellular respiration are removed
from the body.
Explain what happens to “leftover” food materials after
digestion.
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Michigan Department of Education
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Explain the chemical process that occurs in cells to release energy from
food.
Explain why people need to breathe, and where oxygen goes after it
enters the body.
Explain where the carbon dioxide in our breath comes from.
Explain why cells need energy.
Explain how food helps people grow.
Explain what happens when people gain or lose weight.
Explain how cells use food to grow.
Explain how the growth of cells is related to the growth of individuals.
Food, Energy and Growth
TEACHER’S GUIDE
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List of
Materials for
the Unit
Cluster 1
Lesson 1, page 2
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Lesson 2:
marshmallows
shish-ke-bob sticks or something else to hold the marshmallows
matches
safety goggles
5 test tubes
l a grease pencil
l iodine solution
l several foods:
corn starch dissolved in water
glucose (sugar) dissolved in water
gelatin dissolved in water
cooking oil
l other foods for testing such as : banana, oatmeal, cooked egg
white, potato, cracker,apple, spaghetti or noodles, cheese, and any
other foods you want to bring from home to test.
Food Test #l, page 5
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safety goggles
5 test tubes
l a grease pencil
l Benedict’s
solution
l a boiling water bath (water boiling in a beaker, to place test tubes
in)
l several foods:
corn starch dissolved in water
glucose (sugar) dissolved in water
gelatin dissolved in water
cooking oil
l other foods for testing such as oatmeal, banana, cooked egg white,
potato, apple, spaghetti or noodles, cheese, and any other foods you
to bring from home to test.
Food Test #2, page 8
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same set-up as for Food Test #l, except using biuret solution instead
of iodine
Food Test #3, page 10
Food Test #4, page 11
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Lesson 3, page 16
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brown wrapping paper
lamp
foods to test, same as in other food tests (see above)
wet sand
a tray, dishpan, cookie sheet, etc. for containing the sand sculpture
Michigan Department of Education
Cluster 2
Lesson 4, page 18
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Lesson 5, page 19
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outline picture of human body (in appendix)
uncooked oatmeal and a teaspoon to measure it
Benedict’s solution and an eye dropper
(why Benedict’s solution?)
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test tubes
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a boiling water bath
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Lesson 6, page 22
3 Petri dishes without covers
a stirring rod
measuring spoon
unflavored gelatin, set
unseasoned meat tenderizer
crushed fresh pineapple
crushed canned pineapple
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Lesson 7, page 27
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5” by 5” piece of screen
250 ml beaker
course sand (sand with variation in size of grains)
unflavored gelatin, set
unseasoned meat tenderizer
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Lesson 8, page 31
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skematic drawing of cross-section of small intestine and blood
vessels (in appendix)
yam and markers of various colors, straight pins, glue or tape
pictures of food molecules (abstract shapes - in appendix)
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outline picture of human body (in appendix)
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Lesson 9, page 34
The 3-2-1 Classroom
Contact video on the
digestive system Digestion,
The Inside Story) contains a
good view of the small
intestine and other parts of
the digestive system, useful
in this cluster. It is
available from GPN, P.O.
Box 80669. Lincoln. Neb.
68501,806-228-4630.
Cluster 3
Lesson 10, Part 1,
page 36
Lesson 10, Part 2,
page 38
Lesson 11, page 40
. 150 ml Erlenmeyer flask
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150 ml beaker
straws
bromthymol blue solution (BTB)
Alka-seltzer tablets
stopper, glass tubing and hose
50 ml graduated cylinder
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stopwatch or clock with a second hand
150 ml beaker
50 ml graduated cylinder
bromthymol blue solution
straws
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Food, Energy and Growth
butter
cotton string
Petri dish
250 ml Pyrex beaker
scissors
matches
BTB solution
TEACHER’S GUIDE
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Lesson 12, page 45
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model from Cluster 2
“molecules” of protein, fat, and carbohydrate (in appendix)
pins
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calculators
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Lesson 13, page 49
Cluster 4
Lesson 14, page 57
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copies of the Eating Right Food Pyramid (in appendix)
copies of blank Pyramid (in appendix)
chart of composition of various foods (in appendix)
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chart of composition of various foods (in appendix)
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Lesson 15, page 63
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Michigan Department of Education
Laboratory
m Background Information
for Cluster 1
Lesson 1 FOOD CONTAINS ENERGY
P. 2
Students will perform a simple experiment that they are all familiar with but
perhaps have never taken the time to think about and observe. They will light
a marshmallow, watch it bum and make some observations about what is
going on.
Marshmallows, Shish-ke-bob sticks, or something else to hold marshmallow,
splints and matches to light marshmallow
PIT.FALLS AND CAUTIONS
Always be very careful with fire. Large cans of sand should be placed around
the room in case of an accident. Also, there should be containers of water in
which students can drop their marshmallow in case it gets too hot to hold or
if the stick they areusingbums. Tell students to hold the burningmarshmallow
over the container of water so if the marshmallow gets soft and falls off the
stick, the fire will be extinguished.
Lesson 2 WHY EAT HEALTHFUL FOODS
Since iodine changes to a blue-black color in the presence of a starch, it is
possible to use this test to determine if starch is present in various foods. In
Part A of this activity, students will perform the iodine test on a control (water)
and on samples of a starch, a sugar, a protein (gelatin) and a fat. By comparing
the color of the control with the color produced when adding the iodine solution
to each of these nutrients, they will discover which ofthese nutrients changes
color with the iodine solution. They will then use this information to test other
foods to see if starch is present.
FOOD TEST #l
P 4
MATERIALS & PREPARATION
Test tubes, 5 per student group (18 x 150 mm is a good size); grease pencils;
iodine test solution; corn starch solution (1%); glucose solution (1%); gelatin
solution (1%); cooking oil; foods for testing such as banana, cooked egg white,
potato, cracker, oatmeal, apple, spaghetti or noodles, cheese, etc. and other
foods students bring from home.
Solutions must be made up in advance and will be used for testing food in
several activities so you will want to prepare enough for future use.
CORN STARCH SOLUTION
Make a 1% solution by adding 1 gram of corn starch with a small amount of
cold water while mixing. Continue adding water to bring the total volume to
100 ml. Heat the solution to boiling and allow to boil for 1 minute or until the
starch is completely dissolved. Let cool.
Food, Energy and Growth
TEACHER’S GUIDE
lab prep 1
SUGAR SOLUTION
Make a 1% solution by dissolving 1 gram of glucose (also called dextrose) in
water and then bring the total volume to 100 ml. Regular table sugar will not
work for the sugar test done later in this lesson, but you can substitute fructose
(fruit sugar or lactose (milk sugar).
GELATIN SOLUTION
Make a 1% solution by dissolving 1 gram of unflavored gelatin in water and
then bring the total volume to 100 ml. Heat the solution until the gelatin has
completely dissolved.
IODINE TEST SOLUTION
Iodine solution may be purchased from most chemical supply companies as
Lugol’s iodine solution or you may obtain tincture of iodine from the local
pharmacy. These solutions should be diluted by adding one part of the iodine
solution with 5 parts of water. If you wish to make your own, dissolve 2 grams
of potassium iodide (KI) in 100 ml of water. Add 1 gram of iodine crystals and
stir until dissolved.
PITFALLS AND CAUTIONS
1. In order to obtain good test results, foods tested initially should be white or
light-colored. This allows the color of the iodine to show up clearly.
2. Color should be observed where ever the iodine solution comes in contact
with the food. It is not necessary for the whole contents of the test tube to
change color.
3. Iodine, though in very dilute solution, can be harmful and should be handled
with great care. If spilled wash with plenty of water.
4. Students should be encouraged to bring foods of their own choosing from
home. Allow them to investigate foods of any color. They should discover on
their own that it is sometimes difficult to tell if the iodine gave a positive test.
5. Iodine will discolor in any of the unsaturated oils. This should not interfere
with the students ability to determine that the test clearly was not positive.
6. Don’t use small test tubes as the food will get stuck and they will be difficult
to clean.
FOOD TEST #2
P. 8
lab prep 2
Some sugars, called reducing sugars, will react when heated with Benedict’s
solution to produce colors ranging from yellow-green to red-orange. This
activity allows the students to use this test to find out whether a reducing
sugar is present in various foods that they eat. In Part A they will perform a
test with Benedict’s solution on a control (water) and on samples of a starch,
a sugar, and a protein (gelatin) and fat (cooking oil.) By comparing the color
produced when adding the Benedict’s solution to each of these nutrients with
the color of the control, they will discover which of these nutrients changes
color with the Benedict’s solution. They will then use this information to test
other foods to see if sugar is present.
Michigan Department of Education
MATER IALS & ADVANCE PREPARATION
Test tubes, 18 x 150mm (5 per group); test tube holder; grease pencils; hot
water baths; Benedict’s solution; corn starch solution (1%); glucose solution
(1%); gelatin solution (1%); cooking oil; foods for testing such as oatmeal,
banana, cooked eggwhite, potato, cracker, apple, spaghetti or noodles, cheese,
etc. and other foods students bring from home.
Most of these solutions were used in the preceding activity. Be sure you have
enough of each solution for this activity. You will need to prepare the
Benedict’s solution in advance. It will be used for testing food in future
activities so you will want to prepare extra.
CORN STARCH SOLUTION
See p. “lab prep 1”
SUGAR SOLUTION
See p. "lab prep 2”
GELATIN SOLUTION
See p. “lab prep 2”
BENEDICT’S TEST SOLUTION
Benedict’s solution may be purchased from most chemical supply companies
or you may make your own. Dissolve 173 grams of sodium (or potassium)
citrate K!,H,N%O,l and 100 grams of anhydrous sodium carbonate (Na.$O,)
in 800 ml of water. (Note: Instead of anhydrous sodium carbonate, you may
use 200 grams of hydrated (crystalline) sodium carbonate.) Heat the solution
gently to speed dissolving. Filter the solution. Stir constantly while adding
to this solution, 17.3 grams of copper (II) sulfate pentahydrate (CuS0,‘5H,O)
which has been dissolved in 100 ml of water. Add enough water to bring the
total volume to 1 liter.
PITFALLSAND CAUTIONS
1. In. order to obtain good test results, foods should be white or nearly white.
This allows the colors of the reaction to show up clearly.
2. A positive reaction in this test can yield colors ranging from yellow to red
to blue and all possible mixtures of these colors. It is not necessary to
determine why different colors form. Students should simply know that each
of these is a positive test.
3. Benedict’s solution, though very dilute, can be harmful and should be
handled with great care. If spilled wash with plenty of water.
4. A boiling water bath is most easily set up by placing a beaker of water on
a hot plate to boil. Test tubes are placed in the beaker ofboiling water. Water
should be boiling gently, not vigorously.
5. Students should be encouraged to bring foods from home. Allow them to
investigate all of these foods. You may need to remind them that sometimes
the color of the food interferes with the color of the test.
6. Some foods may not give a positive test result even though you and the
student know that it contains sugar. This is because there are some sugars
that are not sensitive to this test. There are other tests that can detect these
Food,, Energy and Growth
TEACHER’S GUIDE
lab prep 3
other sugars.
7. If smaller test tubes are used, the food may get stuck and cause problems
cleaning them.
FOOD TEST # 3
p_ 10
This activity allows the students to find out whether protein is present in
various foods that they eat by adding Biuret solution to various foods. In the
presence of certain proteins, Biuret solution will turn a pink to purple or violet
color. In Part A, students will perform the Biuret test on a control (water) and
on samples of a starch, a sugar, a protein (gelatin) and a fat (cooking oil.) By
comparing the color produced when adding the Biuret solution to each of these
nutrients with the control, they will discover which of these nutrients changes
color with the Biuret solution. They will then use this information to test other
foods to see if protein is present.
MATERIALS & ADVANCE PREPARATION
Test tubes, 5 per group (18 x 150mm); grease pencils; Biuret test solution; corn
starch solution (1%); glucose solution (1%); gelatin solution (1%); cooking oil;
foods for testing such as banana, cooked egg white; potato, cracker, apple,
spaghetti or noodles, cheese, etc. and other foods students bring from home.
Most of these solutions were used in the preceding two activities. You will
need to check to be sure there is enough of each solution for this activity.
Biuret solution was not used before. Solutions must be made up in advance
and will be used for testingfood in several activities so you will want to prepare
extra. Directions for preparing all of the solutions are given below.
CORN STARCH SOLUTION
See p. "lab prep 1”
SUGAR SOLUTION
See p. “lab prep 2”
GELATIN SOLUTION
See p. “lab prep 2”
BIURET REAGENT:
Biuret solution may be purchased from most chemical supply companies or
you make your own. Dissolve 3 grams of copper sulfate (CuSO,*5H,O) and 12
grams of potassium sodium tartrate (KNaC,H,O,; also called Rochelle salt) in
1 liter of water. Next prepare a second solution by adding 60 grams of sodium
hydroxide pellets (NaOH) very slowly with stirring to 600 ml of water.
CAUTION: Use Pyrex glassware as this reaction generates a large
amount of heat. Stir constantly while slowly adding the sodium hydroxide
solution to the copper sulfate solution.
PITFALLS AND CAUTIONS
1. In order to obtain good test results, foods should be white or nearly white.
This allows the color of the Biuret solution to show up clearly.
2. Color should be observed where ever the Biuret solution comes in contact
lab prep 4
Michigan Department of Education
with the food. It is not necessary for the whole contents of the test tube to
change color.
3. Biuret, though in very dilute solution, can be harmful and should be
handled with great care. If spilled wash with plenty of water.
4. Students should be encouraged to bring foods from home. Allow them to
investigate all of these foods. You might want to encourage them to make
predictions about whether the nutrient for which they are testing is present
in each of the foods they test. There will probably be some surprises!
5. Food may get stuck in smaller test tubes and make cleaning up more
difficult.
In this activity, the students will investigate whether various foods contain
fats. This test is done placing a drop of the food to be tested on brown wrapping
paper and smearing it around with your finger or by rubbing a small amount
of the food to be tested directly on the brown wrapping paper. The paper is
then allowed to dry and is held up to a light to see if light passes through it.
FOOD TEST #4
p. 11
MATERIALS & ADVANCE PREPARATION
Brown wrapping paper cut into squares approximately 2” x 2”, gooseneck
lamp or other light source, corn starch solution (1%); glucose solution (1%);
gelatin solution (1%); cooking oil; foods for testing such as banana, cooked egg
white; potato, cracker, apple, spaghetti or noodles, cheese, etc. and other foods
students bring from home.
Most of these solutions were used in the preceding two activities but you will
need to check to be sure there is enough of each for this activity. Solutions
must be prepared in advance.
CORN STARCH SOLUTION
See p. “lab prep 1”
SUGAR SOLUTION
See p. Yab prep 2”
.
GELATIN SOLUTION
See p. “lab prep 2”
PITFALLS AND CAUTIONS
1. If the food contains only a small amount of fat, it may not be detected in this
test. If no fat has been detected, you may allow the students to investigate
further by dissolving a small amount of the food in a few ml of rubbing alcohol.
Allow the food to dissolve for about 5 minutes. Then pour the solution onto a
piece of brown paper and allow to dry. Then check for a translucent spot on
the brown paper.
2. Brown paper bags work well for this test if you avoid using the parts of the
bag with printing on it.
’
3. The light source works well as a heat source to dry the papers. Place a few
inches from the paper after the food has been rubbed very hard into the paper.
Food, Energy and Growth
TEACHER’S GUIDE
lab prep 5
4. Students should be encouraged to bring foods from home. Allow them to
investigate all of these foods. You might want to encourage them to make
predictions about whether the nutrient for which they are testing is present
in each of the foods they test. There will probably be some surprises!
Lesson 3 SAND SCULPTURE
P. 14 This activity is designed to get students thinking about cells as the building
block of all living things. Often students will tell you that all living things are
made up of cells but upon further probinginto their thinking about where cells
can be found, they might say in the skin and blood. When asked about bone,
hair, heart, muscle etc., they will frequently hesitate and then either say “No”
or “I don’t know.” The similarity of cells in all living things and grains in the
sand sculpture should help them realize that all living things are made
ENTIRELY of cells; and like the grains of sand, the cells of living things differ.
There are skin cells, blood cells, muscle cells, nerve cells, etc.
Fine sand and water; trays of some kind to build the sand sculpture on, so that
sand doesn’t get all over the desks and floors (styrofoam meat trays, cafeteria
trays, aluminum trays students bring from home, etc.)
PITFALLS AND CAUTIONS
1. Students may think they are too sophisticated for this activity and they may
have a hard time getting started, but as soon as they begin they usually get
into the creativity of their sculpture quickly. It is important that they do not
lose sight of the comparison between grains of sand and cells of living things.
Going around the room and asking questions to individual students will help
keep the focus on the lesson.
2. You or one of your students may want to bring a camera and take pictures
of some of the sculptures to display around the room.
lab prep 6
Michigan Department of Education
WHY DO LIVING
THINGS NEED FOOD?
PytJ
1
ti
0
Many questions are posed in this unit
simply to stimulate class discussion.
Questions marked with numbers are ones
that students should write answers to.
We recommend that students use a
joumals or “science log” for writing
answers to questions so they can refer
back to their earlier ideas when
appropriate. They can also use the
journal for recording observations and
data from lab activities.
Think about your favorite meal.
Think about all the foods you can buy at the grocery
store or a farmers market.
Think about all the foods advertised on T.V.
Why do you eat the foods you eat? Why does anyone eat
food? What happens to people when they don’t get
enough good food? What happens when they eat too
much "bad” food?
Think of all the foods that are “good for you” that you
don’t like, and all of the "junk foods” that you do like.
Whafs the difference between "good” foods and “junk”
foods?
-
The Key Questions in this unit are
the “objectives” for each cluster or
lesson. When they are first presented
in the cluster or lesson, they are for
stimulating discussion, activating
students’ prior knowledge, and giving
anideaofwhat’s ahead. Don’t ask for
or give definitive answers at this
time-they will be developed during
the cluster. But do ask students to
voice their present ideas. This will
give you some insight into their
thinking, and perhaps stimulate some
initial debate and questions that will
carry through the cluster.
-
Why do people--and all living things-need food?
0
I(ey
Questions
What's the difference between “good” foods and “junk”
foods?
Where is food used in our bodies?
1
Food, Energy and Cmwth
Food, Energy, and Growth
TEACHER’S GUIDE
Lesson 1
9
FOOD STORES ENERGY
We eat for many reasons. The most important is energy.
All living things require energy for life activities. People need energy to run, to
talk, to lift, to smile, to wink-anytime we move our muscles and bones. We need
energy to pump blood through our body (the heart is a muscle, too!) We
need energy to send nerve signals around our bodies, and to
repair parts of our body when we’re injured or sick. Food
stores the energy we need for all of these life activities.
Allow students time to puzzle about
this. You might want to write their
ideas on the board. If students come up
with a good approach, let them try it.
Can you think of something you could do to show that food
stores energy?
Try This
If you have roasted marshmallows before, you know how quickly they will catch
on fire. Would burning a marshmallow show that the marshmallow stores
energy? What do you think? You might want to try burning a marshmallow
again, just to remind yourself of the experience.
To try it, you will need a marshmallow, a shish-ke-bob stick or something else to
hold the marshmallow, and matches. Be very careful to keep the flaming
marshmallow away from everyone’s hair and face.
A. Light the marshmallow and watch what happens. Record observations from
all of your senses (sight, smell, hearing, touch, and taste.)
1. More light and heat are given off
when the marshmallow bums than the
match gave off. This energy must have
come from the: marshmallow.
1. What evidence do you have that marshmallows store energy?
2. a) When the marshmallow burned, did it give off more energy (more light
and heat) than the match did that was used to light it?
2. There is extra energy that did not
come from the match, since the
marshmallow bums longer. This energy
comes from the marshmallow itself, not
the match. It is not produced by the
marshmallow, but is released during the
chemical change of burning.
b) Where do you think all that energy came from?
2
Michigan Department of Educa tion
Lesson Statement: Students wilI observe energy released from a burning marshmallow and relate this UI their body’s need for energy.
Lesson
1
TG2
Purpose: To introduce the concept that food provides all the energy needed for all ‘“life
activities.”
Approximate Time: 1 class period
See Advance Preparation for this lesson, in blue pages prior to this cluster.
Michigan Department of Education
The heat and light that you see during burning are forms of energy that are
released from the marshmallow as it burns. What do you think is happening
inside your body when a marshmallow g i v e off its stored energy? Are there little
flames burning inside your body giving off heat and light?
Probably not. But energy is being released all the time from the food you eat.
Some is heat that keeps your body temperature close to 98.6. F. Some energy
your muaclea work. Some sends signals through your nerves to your
brain. All of your body’s functions require energy.
Imagine this
Writing
Imagine that you and two companions are traveling in a small boat in the middle
of Lake Michigan. Your boat rune out of gas just when you come to an
uninhabited island. You pull into shore and decide the best thing to do is wait
for help to arrive, but that could take several days or even weeks.
You might want to have your students
write a short story about survival on
this island Have them focus on the
food questions, but let them explore
other aspects of survival, too.
You have no food. You have to survive off the land. You and your friends must
decide how to obtain food for this period of time.
3. How might you decide which things would be good sources of food and
4. List food supplies you would be likely to find on this island.
3. Tbe main idea of this qucstion is that
all food comes
plants or animals
that cat plants.
6. List aa many “life activities” as you can for which your body would need
energy.
4. Fruits, nuts, certain roots, stems and
leaves; fish rabbits, deer, etc.
6. Where would you say that energy in the food you eat (including in the
marshmallow) came from originally?
5. Eating, walking, running, etc. arc
common answers; try to encourage
answers that arc not so common, such
as winking, smiling, breathing, etc.
which would not?
*
*
*
One of the main reasons we eat is to get the energy we need for moving, thinking,
pumping blood around our bodies, talking, smiling, and all other life activities.
But is all the food you eat used for energy?
Lesson 2 is about what is in various foods. All foods are made up of different
combinations of a few common types of substances: proteins, carbohydrates, and
.a To understand how you grow and get energy, you need to know about these
different types of food components. That’s what the next lesson is about!
6. All foodcomes directly or indirectly
from plants. Most students will know
aboutfoodchainsorwebs;theimportant
i&a for this unit is that plants store
energy from the sun in food making
tbc sun’s energy available to humans
and all other animals.
3
Food, Energy, and Growth
Lesson
1
Food, Energy, and Growth
TEACHER’S GUIDE
TG 3
W H A T IS IN VARIOUS FOODS?
Lesson 2
You probably know that children and young people need to eat healthful foods
so that they will grow. But what are healthful foods? Is pizza healthful? Are
hamburgers healthful? People have many different opinions about which foods
are healthful. But there’s one way to know for sure. Ask yourself two questions:
Is this food a good source of energy? Is this food made up of the things that will
help me grow?
Discuss the Key Questions; perhaps
write various answers on the board,
brainstorming; or have students write
their own answers. The purpose is to
make students aware of the beliefs that
they presently hold, and get them to
begin to reflect on their adequacy.
More-complete answers will be
developed as the unit progresses.
Many students will say, at this point in
the unit, that we need to eat healthful
foods “because they help us grow,”
without giving any explanation of what
they do inside our bodies (how we use
food.) As the unit progresses, they
need to improve their explanations to
include the functions of food in our
bodies.
But how can you know if a food is a good source of energy, or is made of the things
you need to grow?
What’s the difference between good foods and
"junk" food?
Questions
How could you find out which is which?
If you said that good foods help you grow big and strong, and junk foods don’t,
that’s OK. But don’t you want to know why?
If you said that we can’t eat only junk foods like candy bars or cookies because
they are mostly sugar and can cause cavities or because they have too much fat
and that’s bad for us-don’t you want to know why? If you said that
we can’t eat just fruit because we won’t get enough protein, or because
maybe there’s not enough of something in it that we need-don’t you
want to know why we need protein?
That’s what this unit is about: finding out why we need to eat healthful foods.
The short answer is: It’s important to eat different kinds of foods
because they contain different kinds of materials our bodies need for
energy and for growing.
What are these different kinds of materials? What are foods made of? We don’t
mean like a pizza is made of cheese, bread dough, tomato sauce and toppings, or
like bread dough is made of flour, salt, sugar, baking soda, oil and yeast. But
what are the components of flour, what are the components of cheese, what are
the components of the basic foods we eat?
4
Michigan Department of Education
Lesson
2
TG4
Michigan Department of Education
All foods are made up of a few different components The three
major components in food are carbohydrates (which include sugar
and starch), fats, and proteins. Where have you heard of these before?
Can you think of some ways to tell which of these materials make up different foods?
Try This
Scientists have ways of telling whether or not carbohydrates, fats or proteins
are a part of different kinds of food. They use special chemicals that turn color
when carbohydrates, fats or proteins make up a certain food. You can do the
same tests that scientists use to find out what kinds of substances are a part of
the foods you eat.
Many students have heard of these before
in health class or by reading labels from
food packaging. Some may have done
the food tests before.
Other components of food beside
carbohydrates, proteins, and fats including
vitamins and minerals, a n d fiber.
Vitamins and minerals make up much
smaller percentages of food than
carbohydrates, proteins and fats, but are
still essential for many different body
functions.
You will perform four different tests on several different foods. Two of these
tests are for carbohydrates (one for sugar, and another for starch, both of which
are carbohydrates), one is for fats, and one is for proteins. We won’t tell you
which one you’re doing. You can figure out which is which as you go along.
Food Test #1
For all of these tests, we will start with four very simple foods, and then use a
few more foods that you can bring from home. This will allow you to test some
of your favorite foods.
You will need:
* safety goggles
* 5 test tubes
l agreasepencil
* iodine solution
* several foods:
corn starch dissolved in water,
glucose (sugar) dissolved in
water, gelatin dissolvedin water,
cooking oil.
l other foods for testing such us:
banana, oatmeal, cooked egg
white, potato, cracker,
apple, spaghetti or noodles,
cheese, and any other foods you
want to bring from home to test.
Each of the tests that follow have two
parts. The first parts are samples of food
that have only one component. The
second part uses more complex “‘every
day” foods. To save time, you could do
the first part of each test as a class demo.
We recommend that you stilt allow
students to figure out which test is for
which food component, rather than
simply telling them this.
Most students do not think of the simple
test substances (corn starch, glucose,
gelatin and cooking oil) as foods. They
might need to be reminded that, even
though we don’t eat them straight, they
are also foods.
To keep track of which food you are testing, you will need to put different foods
in separate test tubes and mark each test tube to tell them apart.
5
Food, Energy and Growth
to begin to consider why some foods are “junk” foods, and others are more important for
gI+OWth,
Approximate Time: 1~2classperiodsforeachtestdepen~ngMw~theinitial
testsaredoneasdem~tions~studentIdbs,andhowmanyfoodsafeused.
is 4 to 8 class periods.
LJ
?‘otaMne
See Advance Preparation for this lesson in the blue pages prior to this cluster.
Food, Energy, and Growth
TEACHER’S GUIDE
Lesson
2
A. Use a grease pencil to number five test tubes, 1 through 5. Then make
a line 2 cm from the bottom on each of these test tubes.
B. Fill the test tubes to the line with the following substances:
water (wed as a control)
corn starch solution (starch)
glucose solution (sugar)
gelatin solution (protein)
cooking oil (fat)
Test tube #l:
Teat tube #2:
Test tube #3:
Test tube #4:
Test tube #5:
C. Create a chart in your journal for recording your observations,
something like this:
substance to be iodine solution
test results
tested
The extra rows and columns are for
additional foods (rows) and additional
tests (columns). There arc a total of four
different food tests.
(color)
water
corn starch
solution
glucose solution
gelatin solution
cooking oil
D. Notice and record the color of the iodine solution.
Lab
db
Q safety
The test solutions car irritate your eyes and skinr’n,
skin B e very
careful not to spill them on yourself or others. Rinse in plenty
of water if you spill any. Get help from your teacher.
E. Test each food (and the control) by adding a few drops of the iodine
solution to each of the five test tubes. Observe and record the color
of each food after the iodine has been added to it.
6
Michigan Department of Education
Lists of foods: Yourclassshouldbegin
cl
Lesson
tokeeplistsoffoodsthatcontainsignificantamounts
of sugar, carbohydrates, protein and fat. We want students to develop a familiarity with the major
components of food (for example, that chocolate candy contains sugar and fat; that bread, cereals
and pasta contain starch or complex carbohydrates; that meats contain protein, etc.)
2
TG6
Michigan Department of Education
1. The first test tube, which contained water, was used as a control. How
did the color change when the iodine was added? Is this a new color?
2. Which test substances changed the color of the iodine solution? What
color did it turn?
3. Based on your observations, which component of food (starch, sugar,
protein, or fat) is the iodine test used to detect? Why do you think that?
4. How could you tell if this component is present in a food that you might
eat for dinner?
The control did not change the color of the iodine-it only made it lighter because
the water diluted the iodine a little. Water is used as a control because it shows
what happens to the test solution when it is added to a test tube with no starch,
protein, or carbohydrate.
***
Food Test #l with Other Foods
Now try testing some other foods. Test foods that you like, or that you want to
know more about.
1. The color got slightly lighter. Itisnot
a new color, only diluted; no chemical
change has taken place. Students may
need to be told that-for these tests-it
doesn’t matter how dark or light a color
is: dark blue and light blue are still blue,
only the light blue is diluted by more
water, which doesn’t change the test.
2. Starch; the color changed to dark blue
or black, depending on how much starch
was present.
3. Starch. It reacts with the iodineturns color in the iodine test.
4. You could test a sample of your food
with iodine and look for a color change.
(Some students may know that you can
find this information on food labels.)
F. Keep test tube #l as a control. Use it to compare colors to see if a reaction
occured. Clean test tubes #2, #3, # 4 and #5. You need clean test tubes to
make sure that none of the first foods contaminate the next foods you test.
G . Repeat the iodine test on four new foods. You should use foods that are
mostly white or pale, so you can see the color change easily. Try:
mashed banana
chopped cooked egg white
oatmeal
marshmallows
Record your observations in your journal.
Make sure that you test oatmeal.
It is used again in lesson 5.
H. Select at least three other foods provided by your teacher or that you
brought from home. Test them for the presence of starch. Record your
observations on your journal.
Food,
Energy and Growth
7
How test solutions work: Indicator solutions work by actually reacting withthecomponent
of food that they tcst for, crcating a new substance of a different color. This is a chemical reaction.
If the substance that they test for is not present in the food, there will be no reaction, and therefore
no color change-although if the substance being tested has a good deal of water in it, it may
make the color of the test solution lighter, by diluting it. This is why a control is important
mportant to
see what color the test solution becomes when it is diluted with water, but when it does not react.
Food, Energy, and Growth
TEACHER’S GUIDE
a
Lesson
2
-Ix;7
5. Which foods tested “positive" How do you know?
5. Crackers, bread, pasta, oatmeal,
marshmallows, etc. test positive for
starch because the iodine solution turns
6. What does the positive test tell you about the food you tested?
to dark blue or black.
7. Why would it be difficult if we test this on blueberries?
6. These foods contain starch.
7. They are already dark blue so the
change in the color of the iodine would
be very difficult to detect. Some students
may think blueberries are blue because
they contain starch. Not true. Blue is the
color of the food.
8. Purple grapes, raisins, chocolate, etc.
8. On what other foods might it be difficult to test?
***
Food Test #2: If it’s not starch, then what is it?
Scientists use two other tests that are similar to the one you just did. These two
other tests show if foods contain sugar (another kind of carbohydrate) or protein.
Both use chemical solutions that change color if the sugar or protein is present.
Set up this next set of tests in the same way you set up the iodine solution tests.
The only difference is that this new test solution-called Benedict’s solutionworks only when you heat the food to be tested in boiling water.
You will need:
l
l
l
8
safety goggles
5 test tubes
a grease pencil
TtestttestestTtesthe
solutions
can irritate your
eyes and skin. Be
very carefulnot to
them.
f
Rinse in plenty of
water if you spi11
any. Get help from
your teacher.
Michigan Department of Education
Llesson
2
TG 8
Michigan Department of Education
A. Use a grease pencil to number five test tubes, 1 through 5. Put your
initials on the top of each test tube. Then make two lines, one 2 cm from the
bottom on each of these test tubes and another line 4 cm from the bottom of
the test tubes. You will add food to the first line and the test solution to the
second line.
B. Fill the test tube to the first line with the following substances:
Test tube # l : water
Test tube #2: corn starch solution
Test tube #3: glucose (sugar) solution
Test tube #4: gelatin (protein) solution
Test tube #5: cooking oil (fat)
C. Now add enough Benedict’s solution to each of the five test tubes to fill
it to the second line.
D. Place the test tubes in a boiling water bath for three to five minutes,
or until you see a distinct color change. Then observe the color in each
of the five test tubes. Compare the color with that of your control (water.)
Record your observations in your journal. You may simply add another column to your chart to record your observations.
E. Now do the same test with four other foods-mashed banana, chopped,
cooked egg white, oatmeal, and marshmallow. Look back at the directions
for using Benedict’s solution, and follow them carefully.
F. You may test other foods if you like-some of your favorite foods, or foods
you consider either healthful or “junk.” Just keep a record of your tests in
your journal.
9.
The first test tube, which contained water, was used as a control. What
color was it after adding the Benedicts solution?
10. a) Compare the color of the control test tube with each of the other test
tubes. Which test substances changed the color of the Benedict’s solution?
b) What color did it turn?
11. Based on these observations, what component of food does the Benedict
solution test for?
9
Food, Energy and Growth
9. Light blue
10. a) Glucose or sugar
b) Red to orange to yellow to green
to brown. All of these colors represent
positive tests for sugar. In case someone
asks, the different colors are caused by
different kinds of sugars.
11. Glucose (sugar)
0
Lesson
2
L’
Food, Energy, and Growth
TEACHER’S GUIDE
TG 9’
12. a) Which foods in the second set reacted with the Benedict’s solution?
12.a) bananas, crackers, marshmallows,
etc.
b) Did they all turn exactly the same color?
b) No, some turn reddish, others
c) Can you explain any differences?
greenish.
c) Actually, different kinds of sugar
turn different colors. But students may
suggest that different amounts of sugar
or heat cause the different colors; or they
may come up with other interesting ideas
of their own.
13. They all contain glucose (sugar).
13. What can you conclude about the foods that gave a positive test?
***
Food Test #3: If not for starch or sugar, then what?
There’s one more test that scientists use that is similar to the one you just did.
It uses a chemical test solution called biuret solution.
Think about the four main components of food that you have been testing:
sugars, starches (both carbohydrates), proteins, and fats.
Which two have you already used a test for? Which two could this new test be for?
In letting students set up their own
experiments here, we are trying to help
them become more proficient in the
“Constructing new knowledge”
objective of “Design and construct
For this test, no written directions are provided. You have been through these
kinds of tests at least four times now, and you can probably set up these tests
fairly well yourself.
,/
‘\
scientific investigations.”
.- _-_
0
, /’
--
Biuret solution tests for protein. It turns
pink to purple to violet. You may need
to place a piece of white paper behind
the test tube to notice a color change.
---8,’
First, create a new record page for recording your
resulb. Set it up with a table similar to the ones
you’ve used already.
_’
. .._.
.\~
-
Then, set up the test foods, using the four simple
substances in addition to the control (water).
Remember that test solutions can irritate your eyes
and skin. Be very careful not to spill them on yourself
or others. Rinse in plenty of water if you spill any. Get
kelp from your teacher.
db
Q
You need to add at least 10 drops to each test tube, but you do not need to heat
the foods in this test. If will be helpful if you use a white piece of paper for
a background when comparing the colors of the foods to the color of the control.
When you have discovered which main food component the biuret
solution tests for, make a note in your journal. Then conduct the biuret test
again on new foods such as mashed banana, oatmeal, crackers, marshmallow,
egg white, and any other foods you might have brought from home. Record your
observations and conclusions in your journal.
10
Michigan Department of Education
Lesson
2
TG 10
Michigan Department of Education
Food Test #4: This one’s different!
d
How can you test for another component offoods-fats? The test for
fats is much simpler to perform, but it only works well only with a
’
high-fat content food sample.
62
L ,
All you need is brown wrapping paper, a lamp, and food to test. Begin by testing
the simple substances you used earlier: glucose, corn starch, gelatin and cooking
oil.
A. Get samples of each of those foods. Also obtain several small samples
of other foods for testing, such as banana, cooked egg white potato, cracker,
oatmeal, apple, peanut butter, cookies, spaghetti or noodles, cheese or other
foods.
B. Prepare five pieces of brown wrapping paper, approximately 2” x 2”.
Label each piece of paper with the name of the food substance to be tested:
#l: water
#2: corn starch solution
#3: glucose (sugar) solution
#4: gelatin (protein) solution
#5: cooking oil (fat)
C. Use a stirring rod or eye dropper to transfer a few drops of each test
solution to the appropriate piece of brown paper.
D. Allow the test spots on each sheet of brown paper to dry. When
thoroughly dry, brush dried particles off the paper and hold the paper up to
the light. Compare each of the papers with the control. The property of light
passing through the paper is called translucence. Note whether light passes
through the paper. Record your observations in your journal. Save the
papers for comparison in the next part of this lab.
E . Obtain several more sheets of brown paper. Label them with the names
of the following foods:
#6: mashed banana
#7: chopped, cooked egg white
#8: oatmeal
#9: marshmallow
Food, Energy and Growth
11
How much fat is too much? A certain amount of fat is needed by our bodies for the
production of certain cell structures. But “most health authorities recommend an American diet
with less fat, saturated fat, and cholesterol. Populations like ours with diets high in fat have more
obesity and certain types of cancer. The higher levels of saturated fat and cholesterol in our diets
are linked to our increased risk of heart disease.
“A diet low in fat makes it easier for you to include the variety of foods you need for nutrients
without exceeding your calorie needs, because fat contains over twice the calories of an equal
amount of carbohydrates or protein.” Home and Garden Bulletin No. 232, U.S. Department of
Agriculture, U.S. Department of Health and Human Services, 1990.
Food, Energy, and Growth
TEACHER’S GUIDE
sl
Lesson
2
TG 11
F. Now use your finger to rub each of these foods on a spot on the
appropriate piece of brown paper. Be sure to use a different finger or
wash your finger before handling each food. You must rub very hard as you
are trying to press food into the paper. Allow the paper to dry for a few
minutes. The spot will dry more quickly if you use a lamp placed about 2
inches above the paper. When dry, brush off any dried particles. Hold the
paper up to the light and note whether the spot is translucent (as it was
before in the presence of fat). Compare the results with your samples
in part A. Record the results in your journal.
G. You may test other foods if you like. Keep a record of your tests in
your journal.
14. You can detect fat because it is the
only one that soaks into the paper and
makes the light pass through the paper.
14. Based on your observations of the way the four simple foods and the
control reacted with the paper, which of the four components can you
detect using the brown paper test? Explain your reasoning.
15. Some foods that contain fat are
15. Which of the additional foods you tested contain this component?
cheese, egg yolk, nuts, potato chips, hot
dogs and other meat, etc. Many students
will be surprised to find fats in some of
the foods they tested.
16. On the basis of the tests you have performed in this and the last three
activities, which foods that you tested could be a good source of
a) protein?
b) starch?
c) fat?
d) sugar?
16. Answers will vary but some typical
answers are:
a) egg, cheese, turkey and other meat.
b) crackers, pasta, potato, bread
c) cheese, nuts, red meat
1’7. a) Which foods contained more than one component?
b) Are you surprised by any of these? Why?
d) fruit, cookies, marshmallows
18. a) Did any of the foods contain all 4 components?
17. a) Again answers will vary. Most
foods contain more than one nutrient.
Typical answers might include
marshmallow (starch and sugar),
crackers (starch, sugar and fat), banana
(starch and sugar and maybe fat)
b) Are you surprised by any of these? Why?
b) Answers will vary.
18. a) Possibly nuts or cheese.
b) Answers: will vary.
12
Michigan Department of Education
Lesson
TG 12
Michigan Department of Education
So why is it important to know what’s in foods?
,,
Now that you have completed your food tests, you know that some foodshaveonly
protein, some have only fats, some have onIy starch or ,sugar, but most have
combinations of two or more of these components.
In order to grow and obtain energy, your body must have all of these.subst
substances
ancs
Your body uses many carbohydrates and fats for their stored energy, Your body
uses proteins to build new body parts when it grows or when it repairs itself. The
materialsin food actuallybecome part of our bodies whenwe grow and gain weight
We also use proteins for energy if we
need energy beyond our carbohydrate
and fat supplies. See note on p. TG 48
about vitamins and minerals.
But your body doesn’t need each of these components in equal amounts! Many
Many
of us tend to eat too many foods with lots of sugar and fat (which we need only
in limited quantities) and not enough of the starches and protein (which we need
more of!)
19. a) Use what you have learned to write answers to the two key questions
at the beginning of Lesson 2:
What’s the difference between good foods and “junk” foods?
How could you find out which is which?
b) How are your answers different now than when you first thought
about these questions at the beginning of the lesson?
It is important to understand that some of these food components are used
mainly for energy and some mainly to help us grow. Cluster 2 will go into more
detail about what happens to these components inside your body, and Cluster 3
will go into more detail about how the body uses food for energy and growth.
The last lesson in this cluster explains where food is used in our bodies. Where
do you think?
Food, Energy and Growth
13
Where is food used in our bodies ? Many students believe that food is used in our
stomachs. They have very little notion of the cellular nature of organisms, and that nutrients from
food are needed by cells. If students suggest that food is used in our stomachs, you might get
them to think more deeply about this by asking: If energy is released from food, and if your
muscles need energy when they work, how does the energy get to your muscles. Students
answers to this question are interesting. Some might picture the human body like a giant
electrical circuit, with the stomach being the battery, sending energy out to muscles over wires.
The idea that this unit develops is that the “energy” goes around the body as digested food
(glucose), to be released as needed for various cell activities.
Food, Energy, and Growth
19.a) Students should include the
following key points: Foods that help
you grow must have the proper nutrients
forgrowth. “Junkfoods”have too much
of some nutrients that we only need in
small amounts and not enough of the
others. Many students associate fat and
sugar with “junk food” and think that all
sugar and fat is bad for you. Since each
is a nutrient, your body needs it-but in
smaller quantities than most people eat.
You could determine which
components are present in any
particular food by performing the food
test on the food.
b) Answers vary
TEACHER’S GUIDE
Lesson
2
TG 13
Lesson 3
c3
WHERE THE ACTION IS THE CELLS
Let’s review:
1. People need energy from food for all
life activities; different components from
foodareneededforgrowingwell. (How
cells extract the stored energy in food
(cellular respiration) and how cells and
organisms grow (protein synthesis) are
discussed in Cluster 3.)
1. You have learned that food does two things for people. To the best of your
ability, explain what those two things are
If you said that food gives people energy and helps people grow, you are on the
right track. You also need to say
-why people need energy and
- what it is about food that helps people grow.
Many students have the naive notion
that food goes into their stomach, is
changed in some way, and goes out
through their rectum. Most students
don’t know much about cells. They
might know about blood cells, but only
a few know that cells make up nearly
every structure in our bodies, and that
food needs t o travel to all cells for their
activities.
0
Key
Question
Where do you think that food finally winds up in your
body, so that it can release its energy or help you grow?
If your leg muscles need energy to help you run, does your body actually take food
to your legs?
If your eyelid muscles need energy to wink, does your body have a way ofgetting
food to your eyelids?
Or does food just go to your stomach, get changed somehow, and come out the
other end?
Let’s begin to discuss these questions by thinking about what makes up your
body.
If you look through a very p o w e r microsoope at
skin, what will you see?
S%&
Let students write their initial thoughts
on this question before any class
discussion, then open up discussion for
brainstorming. The idea of cells is
developed through this entire lesson.
If you look through a magnifying glass at the skin on the
back of your hand, you will see skin details-the hairs and
what they come out of, the little cracks on the skin, places
that might be dry and dead.
14
Michigarr Department
of Education
Lesson Statement: After
about what cells are and where they can be found,
students make a sand sculpture as an analogy to the cell structure of living things.
Lesson
3
TG 14
Purpose: To help students reconstruct any prior knowledge about cells and further
develop the idea that every single part of a living organism is made up of cells.
Approximate Time: 1 class period. S e e Advance preparation in blue pages.
Michigan Department of Education
If you use
I
a microscope which magnifies -_1
your skin even more, you can see r
new details. Your skin no longer looks
flat, but bumpy.
If you look through a microscope
with high magnification, your akin
will suddenly look like a collection
of small "pebbles.” What do you
think those “pebbles” are?
Those " p e b b l e s are skin cells. All of your skin is made from millions of these tiny
cells.
Some of you may have heard about cells before. What do people in your class
think they are? Why do they believe what they do?
2. a) What are the tiniest living parts of a heart?
Allow students some time to discuss
what they think cells are, what cells do,
and where they are found in the body.
Also ask them to justify their beliefs
with evidence or reasoning.
2. a) Heart cells
b) What are the tiniest living parts of skin?
b) Skincells
c) What are the tiniest living parts of blood?
c) Bloodcells
If you looked at muscle tissue through a microscope, you would see something very
similar to what your hand looks like under the microscope-millons of tiny little cells
joined together. These cells would be different from the skin cells, but it’s the same
idea: Muscles and skin are made out of cells. Their tiniest living parts are cells, just
as sugar granules are the tiniest parts of sugar.
Are all parts of bodies made of cells? What about brains? Hearts? Stomachs?
Bones? What about the fluids inside your body, like blood?
How could you tell if they were?
16
Food, Energy and Growth
If you have access to microscopes, you may want to let students use them to look at various
objects, including any that show cell structures. (Onion skin and lettuce are good) Prepared
slides are often the best for this. Allow students plenty of time to become adjusted to using the
microscopes-don’t rush it. There are several inexpensive microscopes available for schools
with limited resources.
The video Powers of Ten is helpful for becoming oriented to the small scale of microscopic
views. It’s generally available through REMC’s.
Food, Energy, and Growth
Almost every part of the human body is
made of cells. Bones, for example, are
also extrusions of calcium phosphate.
TEACHER’S GUIDE
Lesson
3
Xi 15
*
At first, students may feel insulted by
the level of this activity, but usually they
will get into the sculpture part of it
quickly. Be sure, however, that they
realize why they are doing this--that
they understand the similarity between
grains of sand of their sculpture and
cells of all living things. Also, help
them realize that just as grains of sand
come in different sizes, shapes and
colors, so do cells in all living things.
Heart cells are: different from skin cells,
anddifferentagainfrom bloodcells,etc.
Their sculpture is different from living
organisms in several ways. The most
important way is that the “cells” in their
sculpture are not organized into tissues
and organs, like the heart, the liver,
bones, muscles, the brain, etc.
Try This
A. Take a cup full of wet sand. Mold and shape it to look like a living
organism of some kind: a person, a plant, an animal. Describe in your
journal how the sculpture resembles a real person, plant or animal. Think
about what each grain of sand represents. Also describe how this sand
model is different from a living organism.
All of your body’s cells are living.
They need food and oxygen just
like all living things do. They
get rid of waste producta, just
like all living things do. They’re
busy all the time, doing all
different kinds of things. You’d
be surprised at the different
activities that go on in cells.
I
So now the question is, does the food you eat go to your stomach, get used
somehow in your stomach, and then go straight out through the other end?
Or does the food you eat perhaps just get changed somehow in your stomach, and
then move to your cells, to be used in your cells? Choose one of these two
possibilities that you think makes the most sense to you at this time. To make
this choice, think about this: Where does your body need fuel for energy? Where
does your body need “raw materials” for building new muscles, skin, blood, etc.
as you grow?
Well continue to talk about where food is used as the unit goes on.
***
3. By now students are beginning to
construct the idea that food has to travel
to every place in our bodies--to all cells-to be used for energy and growth. They
might ask some questions like “Does
food go to the end of your fingers?” or
“Does food go into your brain?”
But they also might still be thinking
that food needs to travel only to those
places where you are growing, or only to
those places that obviously need energy,
like muscles. They should develop an
understanding that every cell in our
bodies has a place in making our bodies
work correctly, and each cell needs
energy.
TG 16
Does this discussion make you think of other questions about food, energy, and
cells?
3. Write any other questions you would like to find answers to in your
journal.
Cluster 2 covers where your food goes after you chew it. You may be surprised!
16
Michigan Department
of Education
Michigan Department of Education
Laboratory Background Information
for Cluster 2
Lesson 4 THE FOOD TRIP, PART 1:
THE DIGESTIVE TRACT
Throughout this cluster students will be drawing their ideas of how food
moves through the body, using an outline picture of the human body. It will
serve two purposes: 1) The students will draw their ideas before instruction,
indicating their prior knowledge and existing theories of how food moves. As
the teacher observes students’ drawings, misconceptions or gaps in students’
information should become quite obvious. 2) Students will be able to add to
the picture as they gain new knowledge. This will help them build the
complete picture rather than having numerous isolated bits of information.
p. 18
MATERIALS
Outline picture of human body (in appendix)
PITFALLS AND CAUTIONS
1. Help students understand that their first paragraphs are not expected to
be complete or perfect. Encourage students to make corrections and add to
them as they learn new information. Their final picture and paragraph should
tell a much more detailed and complete story than their initial one.
2. Be sure students save their pictures. You may wish to collect them and save
them for when they are needed again (at the end of Lesson 6 and 9.)
Lesson 5 DIGESTING FOODS:
WHERE DOES IT START?
The process of digestion begins in the mouth where food is chewed and broken
into small pieces. Then as it mixes with saliva, an enzyme present in the saliva
reacts with starches and breaks them into simpler molecules of sugar.
Students will investigate this process by testing oatmeal before they chew it
and then again after it has been chewed and mixed with saliva. They may also
decide to test the saliva by itself. They are able to see from the tests they
perform that neither the saliva alone or the unchewed oatmeal contain sugar.
Only after it has been chewed and mixed with the saliva does the oatmeal test
positive for sugar. An enzyme in the saliva breaks the larger starch molecules
into smaller, simpler sugar molecules. It is possible to actually taste this
change. At the end of the activity, you might want to have the students chew
a cracker slowly and thoroughly without swallowingit. After a minute or two,
ask them if they can notice a change in the taste. It gets sweeter.
Food, Energy and Growth
TEACHER’S GUIDE
p. 19
lab prep 7
MATERIALS
4 large test tubes (8 if also doing the starch test) 18 x 150 mm, eye droppers,
clean rubber bands or paraffin (chewing on these helps generate saliva),
uncooked oatmeal, Benedict’s solution, grease pencils. You may have these
solutions left from previous labs. If not, see directions on page “lab prep 3,”
in the blue pages prior to Cluster 1.
PZTFALLS AND CAUTIONS
1. HIV concerns: You might want to do this experiment as a demonstration,
to avoid possible transmission of HIV from student to student via saliva.
While research has shown that transmission of HIV through saliva is very
rare, at the time ofpublication new OSHA regulations were being distributed
that might limit these kinds of lab activities.
2. It is very difficult to find a substance that does not have any sugar in it and
will therefore give a negative sugar test before it chewed. If you want to use
crackers instead of oatmeal, be sure to test them first. Oatmeal, even though
dry, really tastes quite good.
3. The purpose of the warm water bath is to simulate body temperature so it
only needs to be warm, not really hot.
4. Students who design their own labs will probably include a starch test as
part of their plan and should proceed accordingly. However, the plan provided
does not include this test but depends on knowledge from activities in the
previous cluster.
5. The flow of saliva in the mouth can be increased by chewing on a clean
rubber band or soft paraffin if students choose to test saliva for sugar.
6. Students may need to refer back to the food tests in Cluster 1 when planning
their food tests.
Lesson 6 MORE ON DIGESTING FOODS:
BREAKING DOWN PROTEINS
p. 22
This activity allows the students to see what happens to protein when it
undergoes digestion. They will use unflavored meat tenderizer (without
MSG) to digest gelatin. The meat tenderizer contains an enzyme (probably
papain, obtained from papaya) that breaks protein into amino acids.
Fresh pineapple contains an enzyme similar to the one in meat tenderizer
called bromelian). As is true of most enzymes, it becomes inactive when
heated. This happens when the pineapple is canned. Students will investigate
the effect of fresh and canned pineapple on the gelatin (protein).
An alternate way to do part B would be to have students prepare flavored jello
with fresh and with canned pineapple. Jello prepared with a substantial
amount of fresh pineapple will not set.
lab prep 8
Michigan Department of Education
MATERIALS
3 Petri dishes without covers; stirring rods; measuring spoons; unflavored
gelatin; unseasoned meat tenderizer; fresh pineapple; crushed canned
pineapple.
Gelatin must be prepared ahead of time and allowed to set. Use unflavored
gelatin and prepare it according to the directions on the package (1 envelope
in one cup ofboiling water.) Stir until the gelatin is thoroughly dissolved. Pour
into a pan so that the gelatin is about l/4" thick. Refrigerate and allow to set.
Cut into 1/2” squares.
The pineapple should be crushed in a food processor or blender until most of
the pulp is exposed. Enzyme activity is mostly in the pulp. But you may want
to try a slice of fresh pineapple directly on the gelatin, since the crushing may
even destroy the enzyme.
PITFALLS AND CAU’I’IONS
1. Since the enzyme activity can occur only where the gelatin is in contact with
the meat tenderizer or pineapple, the gelatin should have plenty of surface
area and be covered on all sides. If it is more than l/4” thick, the reaction is
less obvious.
Lesson 7 GETTING FOOD TO THE CELLS:
MOVING IN A N D OUT OF TIGHT PLACES
p. 27
In this activity, the students will investigate the process of digestion as a
means for breaking down food into very small particles. These particles must
be small enough to leave the intestine (through very small openings or holes
in the walls) and then enter the bloodstream through similar openings or holes
in these very thin walls. Students use sand and a piece of screen as a model.
They should be able to see that sand particles that are small enough can get
through the screen. Other, larger sand particles must be crushed or ground
finer in order to get through the small openings. Similarly in digestion, food
particles are broken into smaller and smaller particles in order to get out of
the small intestine and into the bloodstream. Particles that do not get broken
down or digested continue moving through the food tube to the large intestine
and are eventually eliminated from the body as feces. Students will simulate
the chewingprocess with gelatin that they break or chop physically into small
pieces. They then use the digestive enzyme contained in meat tenderizer to
“digest” the gelatin that has been chopped. They observe it as some of it passes
through the screen and some of it remains in sufficiently large pieces that it
cannot pass through the screen.
Food, Energy and Growth
TEACHER’S GUIDE
lab prep 9
MATERIALS &PREPARATION
Screen (18 or 20 mesh, 5” x 5” or large enough to fit over the beaker or dish
after a depression has been made in it), 250 ml beaker or a small dish, a small
container of course sand (available at hardware stores), unflavored gelatin
(about 1” x 1” x l/4”), mortar and pestle or other means to crush gelatin
(plastic forks work), stirring rod, meat tenderizer.
Gelatin must be prepared ahead of time and allowed to set. See Materials
and Preparation p. lab prep 9, Lesson 6)
PITFALLS AND CAUTIONS
1. Sand should be carefully selected so that some, but not all of it goes
through the screen. Aquarium gravel can be mixed with fine and course
sand.
2. Students will probably suggest that in order for more of the sand to get
through the screen, it needs to be ground finer or pulverized. A good way to
do this would be to provide a mortar and pestle if available. Another way may
be to put the sand into a piece of fine cloth and pound it with a hammer.
3. The digestion of the gelatin will begin somewhat slowly, but within a few
minutes liquid will begin to drip through the screen.
4. Window screen is available from hardware stores. Look for 18 to 20 mesh
(18 to 20 wires per inch.) Plastic screen prevents scratches.
Lesson 8 THE FOOD TRIP, PART 2:
TAKING A RIDE ON THE BLOOD BUS
P- 31
The purpose of this activity is to help students connect their laboratory studies
of digestive processes with the physiology of the body, through the use of a
model. Though the model-building may at first seem a bit simplistic, it is an
important part of the conceptualization that must take place if students are
to thoroughly understand this process.
MATERIALS
Assemble the needed materials into a kit for each group ofstudents: Cardboard
(8 l/2 x 11"), yarn of three different colors (4 feet of brown for digestive system,
6 feet of red for circulatory system, 1 foot of another color for the cells), push
pins and glue, tape, highlighters of three different colors, scissors, diagrams
of digestive system and food particles (in appendix). Cardboard from the back
of tablets works well or you may use tagboard or cut up cardboard boxes.
PITFALLS AND CAUTIONS
1. Since the pieces of digested food are very tiny, they should be pinned to the
board immediately so they are not lost.
2. Do not use oil-based markers instead of highlighters since they will
probably go through the paper and mark the desks. Water-based markers will
work well.
lab prep 10
Michigan Department of Education
3. Some fiber molecules could be added (along with the proteins, carbohydrates, and fats) to show that some of the food particles are too big to get
through the openings. Students should understand from this that not
everything we eat is able to be used by the cells. This unused material is
eliminated from the body. Also, some of the proteins, carbohydrates, and fats
are simply not digested, and also move out of the small intestine to the large
intestine, then out of the body.
4. You may prefer to do this activity as a whole class activity rather than as
an individual activity. Some students will probably not get as full an
understanding as they would if each student (or pair of students) did it
separately.
5. An alternative to using cardboard and pins is to use a flannel board with
yam and pieces of flannel. Another excellent alternative, if resources are
available, is a magnetic board with pieces of magnetic tape with sticky backs
(available from craft stores that deal with cross-stitch.) A small piece of
magnetic tape is stuck to each movable piece and it can easily be moved around
the magnetic board without falling. An alternative to using yarn would be to
color on the diagrams with colored markers. The effect of certain molecules
not being able to pass through the boundary between the small intestine and
the blood vessels is not as pronounced, though, as with yam.
Lesson 9 THE DIGESTIVE AND CIRCULATORY
SYSTEMS: PUTTING IT ALL TOGETHER
p. 34
This activity is an assessment of how students’ ideas have changed from
Lesson 4 to now. They complete their drawing of ‘The food trip” and write
an explanation of what happens to food as it travels through our bodies.
MATERIALS
Students revise and add to the picture they began in Lesson 4.
Food, Energy and Growth
TEACHER’S GUIDE
lab prep 11
lab prep 12
Michigan Department of Education
:HOW DOES FOOD GET
0\-qg
2 A
TO WHERE IT’S USED?
‘WHAT HAPPENS TO IT ALONG THE
WAY?
I?eople eat food because it tastes good. But you know now that you need food for
two far more important reasons.
First, food stores energy, which is released in your body for
all of the activities you do everyday.
Second, the food you eat is needed for growiug and for
repairing or replacing parts of our bodies when they get
damaged or wear out.
Can food be used by our bodies for energy or growth exactly in the form it’s in
when you eat it? Is the food you eat changed as it makes its way through your
body? If food is used in your cells, are there little pieces of meat, little pieces of
cookies, or little pieces of fruit that go to our cells? What happens to the fats,
proteins and carbohydrates in foods?
In this cluster and in Cluster 3 you will investigate, in more detail, how this
happens.
P
Key
Questions
Where does your food go after you swallow it?
What happens to your food as it enters your body?
Food, Energy and Gmwth
Food, Energy, and Growth
These questions don’t need complete
answers now. Students will construct
answers to these questions as they work
through Cluster 2. Right now, many
students probably still believe that food
primarily gets used in the stomach and
excreted, witbout traveling to the cells.
The purpose of Cluster 2 is to establish
the connection between the workings of
the digestive system and the circulatory
system in getting energy-rich substances
and molecular “building blocks” to the
cells.
17
TEACHER’S GUIDE
TG 17
Lesson 4
65
THE FOOD TRIP, Part 1:
The digestive tract
This lesson is a preassessment for
Cluster 2 If students work on this
activity individually, you will have a
record of what they believe before in
structure, which will help you understand
better and respond to their questions
throughout the cluster.
Once you swallow, the food you eat starts on a
fantastic trip down into your body. Think for a
minute about eating a tuna fish sandwich. What
happens to that sandwich after you swallow it?
Where does the food go?
How far can you trace food on its trip into your
body?
1. On an outline picture of the human body
(labeled “My first drawing of the food trip’),
draw in any parts or organs you think your
food goes through, and label them. Use lines
and arrows to show where the food goes.
1. Student pictures will vary greatly in
the parts they include. Some will show
only the mouth, throat, and stomach.
Others might show more. Don’t give
them clues here about what other parts
to include. They should discover these
and add to the picture as you continue
the cluster. Have students keep these
drawings, since they will add to them,
and you may ‘want an opportunity later
in the cluster to talk with them about
some part they included in the early
drawing.
2. Write a short paragraph under the drawing
to explain what you believe about the path
food takes in yourbody, from where it’s eaten
to where it’s used. Explain what youbelieve
happens to food as it travels through your
body.
3. Think of two questions of how,
where, and why food is digested.
Write them on the same page with your drawing and paragraph.
2. Students at this age often think of the
food’s path as going straight to the
stomach, then out through the excretory
organs. Their ideas about what happens
along the way are often vague and naive,
such as “food changes to energy when
it’s digested.”
4. Save your drawing to refer to later.
Most of you probably included a stomach in your drawing. Most people know
that food travels to the stomach. The really important question here is
Does food get used for energy and for materials for
new cells right in the stomach, with the waste products
moving farther down and passing out of the body? Or
does food go somewhere else?
It is important that students
explain the processes in their own
words and not try to use
vocabulary that may have no
meaning to them. If you read some
Be very thoughtful about this question. We talked a bit about cells in Cluster 1.
What do cells have to do with digestion and the food trip?
papers that use complex terms without
explaining them, you may want to ask
those students what they mean by those
words.
18
Michigan Department of Education
3. Answers vary.
Lesson Statement: Students show what they know about the path of food in the human
body by drawing the organs involved in this process on a picture of a human torso and then
writing about the process.
Lesson
4
TG 18
Purpose: To explore students’ prior knowledge about what happens to food after they
eat it.
Approximate Time: 1 class period.
Michigan Department of Education
DIGESTING FOODS:
Where does it start?
Lesson 5
iif
Many of you probably know that food is digested as it travels down into your body.
But what exactly does that mean? Does it mean that food is made into smaller
pieces? Does it mean that it is changed somehow? Is digestion the process of
releasing energy from food?
We’ll explore the process of digestion in the first part of this cluster. We’ll start
in this lesson by exploring where digestion starts.
Where do you think digestion starts?
If you said “Digestion starts in your mouth,” is there a way to find out for sure?
One way to explore what’s going on in your mouth is to chew up some food, take
it out, and see if it has changed in any way.
How can you tell ifit’schanged? In what ways might it change? Has it’s temperature
changed? Has it’s size changed? Did it change intc a new substance?
How could you tell if a new substance is produced? Remember the food tests you
did for starch and sugar in Cluster l? Did you test oatmeal? What was it
composed of? If oatmeal changes in your mouth into a new substance, what
experiment could you do to tell?
In previous food tests, students found
4 Try This
An experiment should include
1) testing oatmeal for sugar-or
protein or fat--before it’s chewed to
show that it contains none; these tests
were done in Lesson 2
2) testing oatmeal after it’s chewed
to discover if it’s changed into sugar,
protein or fat
3) testing saliva by itself to rule out
the possibility of saliva alonecontaining
sugar. Many students will not think
of testing saliva. Page 21 is
designed to help them figure this
out. They can conduct the test on
saliva after they read the top of p.
21.
Talk among your group members about how to test chewed
oatmeal to see if it changes in your mouth. Think through
everything you might want to do. Then write a plan in your
journal.
Your experiment might look like this:
1) Test the oatmeal before it’s chewed, and record your results.
2) Test the oatmeal after it’s been chewed, and record your results.
3) Try to explain your results.
19
Food, Energy , and Growth
Lesson Statement: Students either design an experiment or use the given instructions
to e:xpIore the part of digestion that occurs in the mouth. They perform the tests for sugar
and starch on oatmeal before and after it has been chewed.
Purpose: To investigate both the chemical changes that occur in the mouth as food
begins to uadergo the process of digestion.
Approximate Time; 1 l/2 class periods.
Food, Energy, and Growth
TEACHER’S GUIDE
that oatmeal is composed only of
starch-no sugar, protein, or fat.
Ll
Lesson
5
TG 19
Are you thinking about testing the oatmeal (after chewing) for all of
the components in food? A little thinking before the experiment
might help you decide what tests to do. Remember that oatmeal is
a starch. Starches and sugar are both carbohydrates. Maybe the
starch in oatmeal could change. into sugar. If this is true, you’d have
to do only one test-for sugar.
l
l
(why Benedict’s solution?)
test tubes
test tube holder
. a boiling water bath
Boiling water
burns badly!
Benedict's
solution can
irritate eye8
and skin. If
spilIecl, wash
with plenty of
water. Get
help from your
teacher.
Try your experiment. Use the directions below if you would like to follow stepby-step instructions.
Test the oatmeal before and after chewing:
A. Place approximately 1 teaspoon of oatmeal--out of the box-in test tube A
(or you could label this the 'before” test tube.) Using an eye dropper, add
several drops of water to soften and moisten the oatmeal.
B. Next, chew on approximately 1 teaspoon of oatmeal without swallowing it.
After 1 to 2 minutes, place the chewedoatmeal in test tuhe B (the “after” test
tube.)
C. Place both test tubes in a beaker of boiling water. Wait 5 minutes.
D. Add about 20 drops of Benedict’s solution to each test tube.
E. Heat each of the test tubes gently for 2 to 4 minutes or until a color change
is noted.
F. Record your results in your journal.
Did you find that the oatmeal tested “positive” for sugar after it was chewed?
How can you explain this?
20
Michigan Department of Education
Is chewing a part of digestion? Many biology texts include the physical/mechanical
process of chewing as a part of digestion. Others disagree, arguing that digestion is purely a
chemical process. We have chosen to explain digestion in this unit as only the chemical process
Lesson
5
TG 20
that uses enzymes to change food into new substances. We are purposefully not including
chewing as part of digestion, because it is not a chemical change. Research suggests that many
chemical changes are not really understood by students, who explain them instead as some sort
of physical change. So we are searching for ways not to increase this confusion. Although
chewing increases the surface area of food on which enzymes can act, it does not change food
into a new substance.
Michigan Department of Education
I.. One explanation is that the grinding of the oatmeal by your teeth produced
the sugar. Do you agree? How could you test this?
II. Another possible explanation is that something in your mouth chemically
reacted with the oatmeal to change it into a new substance. If this is true, what
could there be in your mouth that could do that?
III. A third possible explanation is that the saliva in your mouth contains
sugar, and it mixed in with the oatmeal as you chewed. What do you think
about this? How could you test this?
I. You could test this by grinding up
oatmeal outside of the mouth, in a mortar
and pestle, and then testing it
IlI. You could test for sugar already in
your mouth by testing saliva. (It tests
negative for sugar.)
1. Think over the three possible explanations above. Write in your journal
your explanation for why sugar is produced when oatmeal is chewed.
2. Try any tests you can think of to prove or disprove any of the three possible
explanations.
3. Do you think digestion starts in the mouth? If you said yes, what evidence
do you have? If you said no, why?
4. Discuss your explanation with your group partners. After your discussion,
make any changes that will make your explanation better.
1. Answers will vary, but most students
will probably choose one of the three
possibilities stated at top of page.
2. If students test chewed oatmeal for
sugar, they should also test saliva to
determine if it has any sugar itself (it
doesn’t.). This would allow them to
decide on whether they believe the: 3rd
possible explanation (III). (It is often
helpful to chew on a clean rubber band
or paraffm to produce saliva. Students
should not test their saliva after eating.)
3. Digestion is the chemical breakdown
of foods. It begins in the mouth when
salivachemically reacts with starches to
form sugars (simple and smaller
molecules.)
4. If students chose I or III, they may
change to II after testing saliva and
discussing the test results with their
group partners.
-
21
Food, Energy and Growth
Lesson
5
Food, Energy, and Growth
TEACHER’S GUIDE
TG21
MORE ON DIGESTING FOODS:
Breaking down proteins
Lesson 6
@
Think back to your food tests. What kinds of foods have protein in them?
As these foods travel down into the stomach, they are bathed in digestive
chemicals called enzymes. These are new enzymes, different from the ones in
saliva. They help to break down the fats and proteins, as well as the carbohydrates.
Scientists have extracted these chemical enzymes from human bodies. They
know what they’re like. You can actually see what digestion of protein is like,
using enzymes similar to ones in your stomach.
ii) Try This
For a protein, use gelatin, the same protein you used in the food tests in
Cluster 1. Gelatin is a protein that actually helps make up the tendons and
ligaments of animals (the tissues that connect bones and muscles.)
A. Obtain a container of unseasoned meat tenderizer. Bead the ingredients
listed on the container. Record these ingredients in your
journal.
B. Use two petri dishes (covers not needed). Use a grease pencil
to number them 1 and 2.
C. Place one square (about l/2” x l/2”) of set, unflavored gelatin d
in each petri dish. Observe the consistency of the gelatin by
gently poking at it with a stirring rod. Record your observations.
22
Lesson
6
TG 22
Michigan Dqartment of Education
Purpose: To use the digestion of protein in gelatin as a basis for understanding how
protein and fat are digested in the human body.
Approximate Time: 2 class periods.
Michigan Department of Education
Step E requires students to check on
D. Use one square of gelatin as the control (what does that mean?) Then
sprinkle both sides of the other
of gelatin with one-quarter teaspoon of
meat tenderizer.
E. After 2 minutes, poke the gelatin gently with a stirringrod to
check its consistency. You may notice that water also comes
out of the gelatin, but in this activity, you are mainly concerned
with the consistency of the gelatin. Record your observations.
Repeat this test at 5-minute intervals for at least four
observations, more if time permits. Keep recording.
1. At the end of this experiment, how is the control gelatin different from the
gelatin treated with meat tenderizer?
2. Draw a conclusion from your observations: In which case was the
gelatin actually broken down or “digested”-the control or the one treated
with meat tenderizer?
3. Look at the label on the meat tenderizer and decide which ingredient is
responsible for this reaction. The chemical substance which actually
breaks up the gelatin is-can you guess?-an enzyme.
the consistency of their gelatin every 5
minutes over a period of 20 minutes or
so. During this time, you may want to
have them write in their journals first a
prediction about what they might see,
and then their own speculation about
what is happening. That is, their
“observations” might include more than
just a note about the appearance of the
gelatin-they may also include some
analysis of what might be happening.
They should especially come to see the
difference between any water that leaves
the gelatin. and the product o f the
chemical reaction, which might look
“watery.” You may want to ask students
to clarify their notes if they suggest that
the gelatin is tuming watery. Do they
mean that it’s turning into water, or
simply changing to the consistency of
water?
1. The control stayed very hard and
firm while the one with the meat
tenderizer got very soft and liquid-like.
2. The treated one.
3. Usually papain, a derivative of the
papaya plant.
4. Now think about real meat and how meat tenderizer works.
a) Meat tenderizer reacts with which nutrient in meat?
b) What does it do to that component?
c) How do you think meat tenderizer works?
5. a) Explain, in your own words, using a couple of sentences, what happens
to proteins in your body after you eat them. Talk about where the foods
containing protein travel, what happens to them along the way, and what
chemical substance is necessary for this to happen.
b) Add to your drawing and explanation from Lesson 4, or start a new
drawing, to show what you’re learning that’s new. Save your drawings
for later use.
4. a) Protein.
b) It helps digest the protein and
make it soft and not so tough.
c) It is an enzyme that chemically
changes the protein so it can be used by
cells.
5. The key points are:
the protein enters your mouth (where
itiscrushedandgroundas itischewed).
it goes through the esophagus to the
stomach where the protein is mixed
with enzymes that begin to chemically
change it into simpler substances.
it then leaves the stomach and goes
into the small intestine where it is mixed
with more enzymes that continue the
process of chemically changing it into
l
l
6. Speculate: Where in your body do you think the chemical substancethe enzyme-that breaks down protein could come from?
23
Food,, Energy and Growth
6. Students’ answers vary. It may be interesting to
ask them why they think what they do. It comes
from the walls of the stomach and small intestine
and from the pancreas.
Food, Energy, and Growth
TEACHER’S GUIDE
l
I Lesson II
TG 23
The fresh pineapple contains an
enzyme that can break down the
gelatin protein because the canning
process heats the pineapple, destroying
the enzyme. The canned pineapple has
no effect on the gelatin.
In step I: While students are waiting
to check the gelatin at 5-minuteintervals,
you might ask them to consider what
other varialbles are involved in
determining the speed of this gelatin
breakdown (surface area, temperature,
etc. are variables that they may come up
with.) Let them ponder this for awhile,
and perhaps design au experiment to test
out their ideas. If someone came up with
the idea of temperature, they could
develop a hypothesis to test, such as
‘warmer gelatin will break down more
quickly.’
* More fun with enzymes - try a different source:
F. This time, use three pieces of gelatin to test two different substances that
may or may not contain enzymes that can break down protein. The two
substances are 1) crushed, canned pineapple, and 2) crushed, fresh pineapple.
Use three petri dishes without covers, numbered 1 through 3.
G. Place one square (about l/2” x 1/2”) of set, unflavored gelatin into each petri
dish. Observe the firmness and texture of the gelatin by gently poking at it
with a stirring rod. Record your observations.
H. Treat each piece of gelatin as follows:
#l: Control
#2: Place some crushed fresh pineapple directly on top of the gelatin.
#3: Place some crushed canned pineapple directly on top of the gelatin.
I.
7. Usually the gelatin treated with
canned pineapple got a little soft
compared to the control but not nearly
as soft as the fresh pineapple. Students
may say that both gelatins treated with
pineapple were the same because they
think that is what ought to happen rather
than actually observing what actually
happens. Try to encourage them to
really use their powers of observation.
8. The fresh pineapple must have an
enzyme in ithat can break down protein.
9. The canning process must have
destroyed the enzyme. Many enzymes
arc quite sensitive to heat.
After 2 minutes, poke the gelatin pieces gently with a stirring rod to check
their consistencies. Record your observations Repeat this test at fiveminute intervals for at least four observations, more if time permits. Use
your journal to keep track of your observations. Write down any questions
that come to your mind.
7. So what do you conclude? Does either type of pineapple contain a good
enzyme for digesting protein?
8. Here’s an interesting question: My dad says you can’t use fresh
pineapple if you’re making jello with fruit in it, only canned. Why?
9. Speculate: If fresh pineapple originally had the chemical ability to break
down proteins, what do you think happened to destroy the chemical
activity of the enzyme in canned pineapple?
What have we figured out so far about digestion? How close are we to
constructing a good explanation of what goes on with food in our bodies?
24
Michigan Department of Education
Lesson
6
TG 24
Michigan Department of Education
&3
A scientific explanation of digestion
So far in this cluster, you have explored the digestion of two substances, starch
(one type of carbohydrate) and protein. During the digestive process, starches
(and other carbohydrates) are chemically broken down into simpler particlesmolecules-called glucose (one type of sugar.) Glucose is a very small, simple
sugar molecule. You may remember that it is the same sugar that plants form
during the process of photosynthesis. All the starch and other carbohydrates
that you eat in your food (including table sugar) are chemically broken down into
glucose.
This breakdown begins in your mouth and continues in your small intestine.
Chemicals, called enzymes, which cause this breakdown, are in saliva and in
digestive juices found in your small intestine.
Protein in your food does not begin to be digested until it reaches the stomach.
There, the enzymes in the stomach begin reacting with the protein to break it into
simpler molecules called amino acids. Only part of the protein is digested in
the stomach. Most of it passes, undigested, into the small intestine where more
enzymes are produced for breaking down rest of the protein into amino acids.
C a r b o h y d r a t e s b r e a k glucose (simple sugar)
break down into
l amino acids
Proteins
Glucose from carbohydrates is used mostly for energy.
Amino acids are the building materials used for making new cell parts
and repairing old ones. Amino acids make new proteins that become parts
of new cells when your body is growing. Skin, muscle, blood, and hair, and even
enzymes all contain proteins.
25
Food, Energy and Gmwth
The digestive tract is actually over 10 meters (approx. 30 feet) long. Over half of it is the
small intestine. The esophagus (throat) and small intestine help move the food along by
contractions of the muscles in their walls. Muscle contractions-churning-also help combine
the food thoroughly with digestive enzymes. Food remains in the stomach for 2 to 3 hours, and
in the small intestine for 8 to 12 hours.
U
Food, Energy, and Growth
TEACHER’S GUIDE
What about fats? We haven’t done an activity that shows how fats are digested,
but it’s the same idea. In the small intestine, more digestive enzymes break fat
into simpler “building block” molecules called fatty acids.
Fattty acids can bechanged into glucose
if needed for energy, or into amino acids
for building new proteins. Fattty acids
arc also important for several uses in the
body, including making cell membranes, protecting nerve cells in the
brain, making hormones. etc.
break down into
fats - fatty acids
These fatty acids get rebuilt in the cells into new fats.. Some of these new fats
store energy until the cells need it (that’s what body fat is, a place to store food
for when you need energy), and some fatty acids are used in making amino
acids-for making proteins that help make new cells and repair damaged cells.
10. Important points to show on
diagram include:
starches are partially digested in
the mouth but most of the digestion
10. Using the second drawing that you started earlier in this lesson, check it
to make sure that it includes a mouth, stomach and small intestine. Use
arrows and labels to show on the diagram where fate, proteins, and
carbohydrates begin the processes of digestion. (Save the drawing.)
l
takes place in the small intestine; they
become simple sugars called glucose.
proteins are partially digested in
l
the stomach but most of the digestion
takes place in the small intestine; they
become amino acids.
fats arc digested in the small intestine; they become fatty acids.
l
You may want to pose this last question
to your students, either at the end of this
lesson or the beginning of the next, to
help them uncover any prior knowledge
they may have about the circulatory
system. Check their responses t o see if
they talk about “cells.”
Where are we now on the food trip? We’re somewhere in the small intestine. The
food has been chemically changed into new substances-amino acids, glucose,
and fatty acids.
Has the food finished its job at this point? Or is there still more to this story of
the food trip?
26
TG 26
Michigan Department of Education
Michigan Department of Education
-
GETTNG FOOD TO THE CELLS:
Moving through tight places
Lesson 7
You now know that after we eat our food, it is chemically broken down (digested) into
new substances in our mouth, stomach and small intestine. These new substancesglucose, aminoacids, and fatty acids-are used by the cells as fuel for energy and
as building blocks for making new cdl parts.
In this and the next lesson, we will explore two models that show how the food gets
out of the small intestine and begins its trip around our body to all the cells.
-
Key
‘1
Q uestions
You could use the first transparency of
“The Human Body” set (in the appendix&showing only the digestive system-to pose the first “key question.”
How do you think the digested food gets to all of
the cells of your body?
How does it get out of the small intestine?
If you answered y in blood” for the first question, you’re right! Blood vessels are the
delivery system of the body. Think of blood as something like a city bus, following its
route, picking up “passengers” and dropping them off when necessary.
Bllood is constantly moving past the small intestine, picking up digested food and
carrying it everywhere around the body to the cells, dropping a little off here and
there as needed.
Most students’ knowledge of how bodies
use food ends after digestion. They
rarely think of it as having to reach all of
the cells before it can be used by our
body.
Not everything that enters your mouth can get a ride on the blood bus, though.
You’ll figure out why as you try these activities.
l
You will need:
l 8 piece of screen (5’” x 5” or large
9 Try This
l
A. Place the screen over the beaker
and shape it to make a depression
in the middle.
l
l
enough to fit over a beaker or small fish)
a 250 ml beaker or a small dish
a small container of coarse sand
more unflavored gelatin (a piece about
1” x 1” x l/4”)
Mixing aquarium gravel with fine and
course sand works well.
B. Pour the sand into the depression in the screen. Use a spatula or your finger
to stir it around in the screen. Does all of the sand go through the
screen? Record your observations in your journal.
Food, Energy and Growth
27
Lesson Statement: Students use window screen with l)sand and gravel and 2)gelatin
and enzymes and decide which particles pass through the screen. They devise ways to
make more particles go through it. Finally they relate these ideas to the passage of food
from the small intestine to the blood stream.
Purpose: To use several modeIs to help understand how digested food particles pass
through the wall of the small intestine and into the blood stream.
Approximate Time: 2 class periods
Food, Energy, and Growth
TEACHER’S GUIDE
cl
Lesson
7
TG ;!7
1. The size.
1. What property of the sand particles determined whether they passed
2. Crush what didn’t go through the
first time and then try again.
Unfortunately, this is where this
analogy breaks down. Crushing is
like chewing. It works for getting
gravel through screen, but it’s not
what happens in the digestive system,
and crushing gelatin alone will not
really allow more to pass through the
screen (some will if you push really
hard.) The gelatin, made of very long
molecular chains. is still composed
of long chains even if it is crushed or
brokenintosmallpieces. Theenzyme
actually breaks the long molecular
chains into shorter chains, just as
enzymes in the stomach and small
intestine do to proteins..
through the screen or not?
2. How could you make more of the sand particles pass through the screen?
If possible, try out your suggested method.
C. Use the same piece of screen you used with the sand. Get a piece of
“undigested” protein (gelatin).
D. Crush or chop the gelatin into small pieces with a mortar and pestle or by
some other means you or your teacher devise.
E. Place the screen over the beaker or dish as in part A above and place the
gelatin into the depression on the screen. Will the gelatin go through the
screen? Record your observations on your data sheet
.
SF
3. How might you be able to get the gelatin to go through the screen?
3. Allow students to speculate about
this. If any come up with good
suggestions, perhaps you might want
to have the class try them. The
approach used in F-H is to “digest”
the gelatin using meat tenderizer.
Ifyoucan’t think of a way to get the gelatin to go through the screen, here’s a hint:
What happens to it when it’s ‘digested”? Could you “digest” it?
F. Make a small depression in the middle of the gelatin in the screen and place
about l/4 teaspoon of meat tenderizer on the gelatin in this depression. Use
a spatula to stir the meat tenderizer into the gelatin. Be sure the gelatin and
meat tenderizer are well mixed. Observe carefully for a few minutes.
G. Stir occasionally. After about 5 to 8 minutes, add a little more meat
tenderizer. Mix well.
H. Observe for about 5 t.c 10 minutes more. Record your observations.
28
Michigan Department of Education
Lesson
7
TG 28
Michigan Department of Education
-
3.
a) How is crushing or chopping the gelatin similar to what happens to the
food we eat?
b) If physically crushed gelatin can’t get through the screen, what else
could be done to it to get it through?
4. You probably noticed that not all the gelatin passes through the screen.
Why do you think that is?
You already know that enzymes in your small intestine chemically change
proteins into smaller, simpler “building block” molecules-just like meat
tenderizer changes gelatin into different, smaller pieces. The gelatin may not
seem to have changed into a new substance, but it has. The meat tenderizer
chemically changed the gelatin into different molecules, smaller than the
original gelatin protein molecules. As a new substance, it could fit through the
screen.
Here’s what happens after food is chemically changed into different, simpler
molecules: The new molecules pass through very small openings in the
wall of the small intestine and enter the bloodstream They’ve made it onto
the “blood bus”!
I
5. a) If the gelatin in our experiment represented the food you eat, what did
the meat tenderizer represent?
3. a) It is similar to breaking food by
chewing and churning in the stomach.
b) The food needs to be chemically
broken down by an enzyme.
4. The particles that have not been “digested” (broken down) are too big to get
through the holes in the screen. Students
may refer to the substance as being too
thick or say that it didn’t turn into a
liquid. If they say this, they are probably
not thinking of the substance as made of
tiny molecules. Remind them that even
liquids are made up of molecules. This
idea of food being composed of
molecules is essential to students
understanding how digested food passes
through the intestinal wall.
5. a) Enzymes.
b) The walls of the intestine.
b) What did the screen represent?
6. Write a few sentences about what the wall of the small intestine might be
like so the digested food can pass through it and into the bloodstream.
6. Following the sand/screen analogy,
the walls of the small intestine might
have little openings or holes in it that
allow the simpler, digested food particles
to move through, big enough to let
digested food out, but not big enough to
let any undigested food out. See
comment below.
29
Food, Energy and Gmwth
Food movement from the small intestine into the blood stream: Themolecular-level
picture we’re developing of food movement across the small intestine wall is simplified for the
purposes of teaching at this grade level. Actually, there are several mechanisms at work here:
Small molecules can pass through the small intestine wall and dissolve into the blood stream,
but they have to be soluble to do this. Fats are not soluble, but fatty acids are. Also, there are
molecular “carriers” that help transport molecules of digested food across this interface. The
central idea for this unit is that the process of digestion is a chemical one, resulting in simpler,
new “building block” molecules and glucose. It is these new, simpler molecules that pass into
the blood, to be transported to cells.
Food, Energy, and Growth
TEACHER’S GUIDE
i’
Lesson
7
TG 29
Moving digested food to the cells
After your food has been broken down into its simplest form, it moves out of the
One reason that fats don’t go into the
blood stream but fatty acids do is that
fats are not soluble, but fatty acids are.
digestive tract into the bloodstream through millions oftinyfinger-like projections
in the wall of the small intestine (called villi.) The food actually dissolves in the
blood as individual molecules (just like sugar dissolves in hot tea or coffee.) Look
back at your paragraph in #7 and add to it-if you left out something.
The pumping action of the heart and
other body muscles forces the digested
food through millions of blood vessels to
cells all over the body, where the
materials from food are used.
You might want to ask students to
speculate and debate now on what the
oxygen is for. Many will simply say that
you need it to live, or that without it
you’ll die from asphyxia or by
suffocating. Neither one of these answers
really tells how it’s used in our bodies.
But don’t feel like you have to explain
this now. Thi s question is only setting
the stage for a discussion of cellular
respiration in Cluster 3.
But isn’t there something else that moves around the body in the blood? Yes!
blood also carries oxygen from the lungs to all cells. What’s the
You11 look carefully at what the cells do with food and oxygen in Cluster 3.
***
Is there anything in food that isn’t used by the cells? Yes! In the same way that
not all of the gelatin and not all of the sand gets through the screen, not all of the
stuff that goes into your mouth gets through the walls of the small intestine.
Some of the food you eat cannot be broken down, and remains in the small
intestine. It moves into the large intestine and then out of the body as feces. This
is what feces mostly is-undigested or undigestable food.
How do you think the weight of your feces compares to the weight of the food you
eat on a daily basis?
This weight idea will come back again in Cluster 3!
30
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Lesson
I
TG 30
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Michigan Department of Education
Urine, perspiration, and water in the body: Some students may ask about urine at this
point. Urine is the body’s way of getting rid of soluble wastes created in several places.
Sometimes urine is also considered a way of getting rid of water-produced by cells during cellular
respiration (discussed in Cluster 3, Lesson 11.) This is not really the case, since all terrestrial
animals constantly need to drink water. Water produced in cellular respiration basically adds
to what’s already in the body. Water in the form of perspiration is also used as a cooling
mechanism, by carrying off excess body heat when perspiration evaporates from the skin.
Michigan Department of Education
THE FOOD TRIP, PART2:
Taking a ride on the blood bus
Lesson 8
.!S
In the activity you just completed, you saw that food is broken into simpler pieces,
first in your mouth, and then in your stomach and small intestine. You will now
try to further visualize how this process takes place in your body by building a
model that traces the path of food from the small intestine to the various cells of
the body.
*
Try This
Get the kit of materials you’ll need for this
activity.
A. Tape or glue the drawingofthe digestive
system to your piece of cardboard.
B. Use a red marker to color the blood
vessels (dashed lines) red. Use the red
yarn to outline the walls of the blood
vessels. The walls of the blood vessels
are very smooth but may have many
branches.
C. Similarly, use a dark piece of yarn (not
red) to outline the walls of the small intestine. The small intestinal wall has
very wavy lines, much like corrugated paper. Pin or glue the yam in place.
This cross-sectional picture of the small
intestine shows just a small portion of an
organ that is many feet long. For a good
view of the digestive system,
including the small intestine, use
the 3-2-l Classroom Contact
video on the digestive system,
available from GPN, P.O. Box
80669, Lincoln, Nebraska, 68501,
800-228-4630.
At first students may think of this activity
as too simple, but they usually get quite
involved in it as they begin to see how
digestion really works. This activity
seems to help students conceptualize
and remember this process of breaking
down foods into simpler molecules
which can then pass out of the digestive
system and into the circulatory system,
to travel to the cells.
D. Use the third and fourth color of yam to outline the cell membrane of one of
the cells shown on the diagram.
E . Locate and label each of the following parts: intestine wall, intestine
interior, blood vessel wall, interior of blood vessel, and cell.
F.
Now find the pictures of food particles labeled carbohydrate, fat and protein.
Use highlighters to color each of these a different color. Then cut them out
and place them inside the intestinal cavity. Use pins to hold them in place.
31
Food, Energy and Growth
Lesson statement: Students make a model of the small intestine, blood vessels and
cells, and use pictures of food particles to simulate digestion. They actually move these
particles from the small intestine to the blood vessels to the cells to simulate the transport
of digested food.
Purpose: To continue to follow the path of digested food as it is transported~fiom the
small intestine to all the cells of the body
Approximate Time: 2 class periods
Food, Energy, and Growth
Although much more expensive, there
are 3-dimensional fabric paints available
in craft and fabric stores that also work
very well for this activity, and are faster
and easier to use than yarn.
TEACHER’S GUIDE
Lesson
8
TG31
What is missing in your picture that will enable food to get out of the small
intestine and into the blood stream?
G. Make several openings in the intestinal wall by cutting away small pieces of
yam (no more than I/4 inch).
H. Similarly, make several small openings in the walls of the blood vessels.
I.
Where else do you need to make openings for the food to be able to finish its
trip to the cell? Make these openings into the cells by cutting away small
pieces of yarn through both membranes of the cells. Use the free ends of the
yam to connect the inner and outer membranes together.
J.
Now the food can make its trip from the small intestine to the cell. Or can
it? What did we forget? The food particles cannot get out through the
openings unless they are broken down into smaller pieces. Cut each of the
food particles, the carbohydrate, the fat and the protein on the lines. The
colors will help you remember what kind of food particle each is. You may
also wish to put a small “c" on each part of the carbohydrate, a small
on
each part of the fat and a small "p” on each part of the protein.
-
As students near the end of this activity,
you may want to go around the room
with a tape recorder and ask each student
one or two questions. Later you could
play back the best responses as a “radio
broadcast.” Students usually like to
listen to themselves on the tape, and
usually take time to prepare good
answers when they know they are being
taped.
protein
K Now the food particles are ready to make their trip to the cells! Move the
particles through the openings from the small intestine, to the blood stream
and finally to the cells. Be sure that if you move them, they fit through the
openings.
L. When digested food arrives at the cells, they are ready to build new
materials! (Save this model... there’s more on building new materials in
Cluster 3.)
32
TG 32
molecule
Michigan Department of Education
Michigan Department of Education
1. Proteins change into amino acids,
carbohydrates into glucose, and fats into
fatty acids.
Lets review what we’ve talked about so far:
(I
1. Create a table in your journal that tells what substance each component
of the food you eat changes into when it is digested.
2. What has to happen to food so that it can make the trip out of the small
intestine and into the cells?
3. a) Was all of the food able to get out of the small intestine? Why or why
not?
b) What happens to the particles that don’t get out.?
4. Speculate: Why must new materials be assembled inside of the cells
rather than being assembled and then transported?
5. a) The picture you have assembled shows only one specific cell of the
organism. How many other kinds of cells can you imagine there must be
in your body?
b)) Name at least ten kinds of cells that need to get food.
Brick by Brick: Digestion is like taking a building apart, brick by brick, so you
can use the bricks to build (and power) a new building. During the process of
digestion, the large molecules of the food we eat, like the building, are torn down
and chemically changed into simpler molecule-the bricks. These bricks are
then carried to another location, where they are used to build a different
building.
The bloodstream (the bus) is what carries the simpler molecules to all the cells
of your body. The cells then use the “building block” molecules to make the exact
proteins or fats they need to grow, to repair damaged parts, or to store energy for
l.ater use. And they use the glucose molecules for the fuel needed by the cel1 for
powering everything that cells do.
Exactly what goes on in cells with the digested food-how cells extract the energy
stored in glucose, and how they use amino acids to grow and repair themselvesis discussed in Cluster 3!
33
Food, Energy and Growth
What’s feces? Indigestible food (like fiber), bacteria, mucus, dead cells, and food that just
didn’t get digested: and 75% water. It’s the bacteria that produce the odor; as they feed on
leftover and indigestible food, they produce gas. Some foods (notably beans and cabbage) are
for a 1,arge part not digested, leaving lots for bacteria to eat, and producing lots of gas.
Food, Energy, and Growth
TEACHER’S GUIDE
2. It has to be chemically changed
(digested) into new molecules that can
pass through the small intestine wall.
3. a) No, some of the food molecules
were too big to get through theopenings,
like the fiber molecules. If students say
“there weren’t enough enzymes,” make
sure they know what the function of the
enzymes is-to break down the parts of
the food that are digestible-and that
they aren’t just parroting back a key
word without understanding what
enzymes do.
b) They move from the small
intestine to the large intestine and out of
the body as feces.
4. We begin to answer this question on
the bottom of this page (“Brick by
Brick”); a more-complete answer is
developed in Cluster 3. It is interesting
to listen to students’ speculations,
though, and you should encourage this.
We are referring to amino acids as
“building blocks” because they are reassembled into different proteins in the
cells, depending on the individual cell’s
need. Each cell is responsible for
synthesizing its own proteins (following
directions in its DNA). The purpose
(function) of digestion, then, is to take
apart the food we eat, (which has been
built up in other organisms into their
“body parts”) into the amino acids, fatty
acids, and glucose we need for making
new body parts and storing and releasing
energy.
5. a) Answers will vary.
b) Additional cells mentioned might
include skin, blood (redandwhite), brain,
nerve, liver, muscle, egg, sperm, etc.
Lesson
8
TG 33
Key concepts that should be
included are:
the digestive system includes the
mouth, esophagus, stomach, and small
intestine.
l
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digestion begins in the mouth.
the enzymes in saliva change some
starch into sugar.
THE DIGESTIVE AND
CIRCULATORY SYSTEMS:
Putting it all together
Lesson 9
.:
63
In the first lesson of this cluster, you explored your beginning ideas about the
path that food follows in your body and what happens to it along the way. In the
lessons that followed, you experimented with chemically changing food, just as
it’s changed in the digestive system. You also built models of how food moves
from the digestive system, through the circulatory system, to the cells, where it’s
used.
l
l
enzymes in the stomach begin to break
down proteins into amino acids.
enzymes in the small intestine
continue to break down starch and
l
You might have discovered that your ideas about what happens to food changed
as you worked through this cluster. Now would be a good time to finish your
second drawing of the human body (from Lesson 6). This will be a good way of
organizing all you know about where food goes after you eat it, and what happens
to it to prepare for its arrival in the cells.
protein while other enzymes in the small
intestine breakdown fats into fatty acids.
A. Check your drawing to make sure that it includes the major parts of the
digestive system. Label each part with its name.
glucose, fatty acids and amino acids
are small enough to get out of the small
intestine, into and out of the circulatory
system (which carries it to cells) and
finally into each and every cell.
B. Add to your drawing the path that digested food takes to get to a cell in a leg
muscle and maybe a cell in your brain. Label this “path.”
all cells use digested food for energy
and growth.
D. Then write a short essay. Pretend that you’re a piece of food-pick out one
of your favorites-and write a story about what happens to you after you’re
eaten.
l
l
undigested food passes from the small
intestine to the large intestine and then
out of they body as feces.
C. Think about how a heart would fit into your drawing, to show how blood is
pumped around the body. Add the heart and attach it to the blood vessels.
l
You might write a list of words on the
board that students should use in their
story, such as: digestive system,
circulatory system, digest, mouth, small
intestine, enzyme, stomach, aminoacid,
cells, blood vessels, glucose, fatty acids.
You might have students participate in
formulating the list.
E. How did your ideas about what happens to food inside your body change as
you worked through this cluster?
F. What questions do you have at this point about how our bodies use food?
Now get ready to shrink yourself down to the size
of a cell and think about what goes on in every
living part of your body!l On to Cluster 3 !
34
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Llesson
9
TG 34
Michigan Department of Education
Lesson Statemeat: Students complete the picture they made at the beginning of the
cluster and write a story about the food trip as a way of solidfyng what they learned in
this cluster,
Purpose: To pause and think and write about what has been learned about the food trip
and to see what questions remain.
Approximate Time: 1 class period.
Michigan Department of Education
Laboratory Background Information
for Cluster 3
Lesson 10 Breathing and Exercise
p. 40
In this activity, students first determine that they exhale carbon dioxide, by
blowinginto a solution ofbromthymol blue, and then measure their breathing
rate, pulse rate, and “carbon dioxide” rate before and after exercise. They
discover that after exercise they are breathing faster, their pulse rate is faster,
and they are exhaling more carbon dioxide. These measurements provide
evidence about what is happening when the body uses food for energy:
specifically, that more oxygen is required, and more carbon dioxide produced.
This evidence sets the stage for a molecular explanation ofcellular respiration
in Lesson 11.
MATERIALS & ADVANCE PREPARATION
Stopwatch or clock with a second hand, alka seltzer tablets, one 150 ml
Erlenmeyer flasks fitted with a l-hole rubber stopper through which a short
piece of glass tubing attached to a piece of rubber tubing has been inserted (see
the illustration in the lesson), one 150 ml beaker, bromthymol blue solution,
straws, 50 ml graduated cylinder. The glass tubing should be inserted just to
the bottom of the rubber stopper. The rubber tubing must be long enough to
be submerged into the bromthymol blue in the beaker. Bromthymol blue
solution must be made up in advance and tested for how fast it reacts. It will
be used for several activities so you will want to prepare enough for these
activities also.
BROMTHYMOL BLUE SOLUTION (BTB)
Bromthymol blue solution may be purchased already prepared from most
chemical supply companies or you may prepare your own as follows. Prepare
a 0.145 solution by dissolving 0.5 grams ofbromthymol blue in 500 ml of water.
To thiis add ammonium hydroxide (NH,OHl or sodium hydroxide (NaOHl,
drop by drop, until the solution is a deep blue.
In either case, test the solution to determine how much time is required to
change the color from deep blue to yellow by placing about 50 ml of the solution
into a clean beaker. Blow into it through a straw noting the time required for
the color to change from blue to yellow. If less than about 20 seconds is
required, add 2 or 3 drops of the hydroxide solution to it and re-test. If more
than about 40 seconds is required, dilute the solution with about 25 ml of
water and retest. Continue adjusting until the time required to change the
color is between 20 and 40 seconds.
PITFALLS AND CAUTIONS
1. Make sure that each student uses her or his own straw for blowing into the
BTB. Sharing straws is not an acceptable health and safety practice in labs.
2. When testing the alka-seltzer, if the glass tubing extends too far into the
flask, the fizzing and bubbling alka-seltzer will get into the tube and carry over
into the bromthymol blue. This should be avoided, since the test should be
only for the carbon dioxide given off.
3. “Carbon dioxide rate” is not as much a rate as it is the time it takes to change
BTB from blue to yellow, whichgoesdown after exercise, not up, like breathing
rate and pulse rate. It might be less confusing to talk about a faster or slower
rate (e.g. 20 seconds after exercise is faster than 40 seconds before exercise.)
Food, E n e r g y and Growth
TEACHERS GUIDE
lab prep 13
4. For accurately determining“ carbon dioxide rate”, the amount ofbromthymol
blue solution must be exactly the same for the before- and a&r-exercise tests.
More or less solution would require more or less carbon dioxide to make it
change. Use a 50 ml graduated cylinder to measure exactly 50 ml of BTB.
Also, make sure that students exhale only until the solution has turned
completely yellow. The second solution should be the same color as the first
in order for data to be comparable.
5. Students should make all measurements, breathingrate, pulse and carbon
dioxide measurement as quickly as possible after finishing exercising. Since
the increased need for oxygen drops off rapidly,so do all of these measurements.
11 HOW DOES YOUR BODY
ACTUALLY GET ENERGY OUT OF FOOD?
Lesson
p. 46
In Lesson 10, students discover that their bodies need oxygen (with food) for
energy, and that carbon dioxide is given off in the process. In this lesson, they
compare the evidence from Lesson 10 with the actual burning of food
(butter). The burning requires oxygen, and produces carbon dioxide,releasing
heat and light energy.
MATERIALS AND ADVANCE PREPARATION
Butter, cotton string (cut to l”), Petri dish, 250 ml beaker, matches, BTB
solution.
See p. “lab prep 12” for instructions for preparing BTB.
PITFALLS AND CAUTIONS
1. Use real butter or you may have difficulty getting the candle to bum.
2. You can bum a peanut orwalnut, butitmay behardertotestforC0,. Also,
the butter allows students to think about differences between melting and
burning, physical and chemical changes.
3. The butter candle usually goes out rather quickly under the beaker, and
the water level rises. This is because, molecule for molecule, there is less
carbon dioxide produced than oxygen used, reducing the pressure inside the
beaker.
Lesson 12 GROWING
p. 52
Students now complete the picture of how food is used in their bodies by using
their models from Lesson 8 to simulate the formation (synthesis) of new
proteins from the amino acids in the food they digest.
MATERIALS
Models of The Food Trip that students made in Lesson 8; diagrams of food
particles (in appendix); scissors; pins
Lesson 13 WEIGHT GAIN AND WEIGHT LOSS
P. 56 Students consider the eating and exercise activities of two hypothetical teenagers, and the activities’ effects on weight gain and weight loss. They
prepare a “balance sheet” of what goes into a person’s body and what comes
out.
MATERIALS
A copy of the completed balance sheet is included in the appendix.
lab
prep
14
Michigan Department of Education
HOW AND WHERE IS FOOD
USED IN HUMAN BODIES?
a*:@@
va
Have you ever had the experience of waking up late and rushing off to school
hungry? Or have you been involved in some activity and had to postpone dinner
for several hours? Can you remember how you felt? You probably had that
hungryfeelinginyour stomach, but wasyourbodytiredtoo-didyoufeellikeyou
didn’t have very much energy?
In this cluster, we will take an imaginary trip down into the cells to see how they
actually use food to supply the energy you need, and how cells actually use the
building blocks of food to help you grow and repair damaged body parts.
In Cluster 3, you will try to come up with answers to two very important questions:
0 Key
b
The key questions are the objectives
for this cluster. Students should be able
to answer them by the end of the cluster.
How do we get energy out of food?
I
Questions
Why do you have to eat well in order to grow?
Take a few minutes to write down your ideas about each ofthesequestions. Also,
write any additional questions that might come to your mind as you think about
them.
/
I
I.\
P
I
I
SOME OF THE
OF A(JTIVITIES
THAT YOU PERFORM EVERYDAY:
l
l
l
l
hIlLLIONS
I
I
moving your legs when you run
moving the muscles of your face and
vocal cords when you talk or laugh
causing electrical signals to move
through your nerves when you touch
something hot
making new skin to cover over a cut
As you do more of this cluster, your answers to these questions will probably
become more detailed and more in-depth. They might even change as you think
about how our bodies really use food.
Food, Energy, and Growth
Food, Energy, and Growth
35
TEACHER’S GUIDE
TG 35
BREATHmG AND EXERCISE
How can we figure
energy?
Teachers should encourage students to
speculate on these key questions, but
not answer them completely now. The
answers will be constructed by students
as they work through this cluster.
Most students know that we breathe in
oxygen and breathe out carbon dioxide,
but rarely do they relate the need for
oxygen with energy production. They
often don’t have any idea about what
happens inside the body to oxygen, or
where exhaled carbon dioxide comes
from. Some have the naive belief that
the oxygen just changes into carbon
dioxide in the lungs-in which case
they probably don’t have a good
understanding of chemical changes.
Lesson 10
f#
out what’s going on inside your body when you use food for
We can get evidence about what’s going on inside your body when you use food,
by thinking about what happens to your body when you speed up your activitiessuch as when you run or play basketball. This is a time when you really need
energy--so you must be using food quickly. What happens to your body when
you’re exercising?
One thing that happens to your body is that you breathe faster. Why is that? Does
your body need more oxygen? For that matter, why do you breathe at all?
f
does your body do with the oxygen you breathe
I What
in?
Key
Questions
Why do you breathe faster when you exercise?
What comes out of your body when you exhale?
And what does
breathing have to do with food?
We’ll be working on answers to these questions in this lesson and Lesson 11.
eTry
This
In this activity, we will gather some evidence about what’s going on in your body
when you use food.
Have students read through the
entire e x p e r i m e n t b e f o r e
conducting it, creating a chart for
data collection that has spaces for
breathing rate, pulse rate, and “carbon
dioxide rate” both before and after
exercise.
El
Michigan Department of Education
Lesson
10
TG 36
Michigan Department of Education
Part 1. Check and record your breathing rate and pulse rate
A. You need to have a clock or watch with a second hand
available where you can watch the time. Count the
number ofbreaths you take in 60 seconds-your normal
breathing rate per minute. Record this in your
journal.
B. Similarly, count your pulse for 60 seconds- your
normal pulse rate per minute. Record this
journal.
Part 2.
Test your breath for carbon dioxide and record your
“carbon dioxide raw
Read these directions completely before beginning.
C. Fill a beaker about 1/3 full with BTB solution. Use a straw to blow into the
beaker until the color no longer changes. Record all the color changes you
observe.
“Carbon dioxide rate” is in quotes to
indicate that it is not really a rate, but
simply the amount of time it takes to
turn BTB yellow. Shorter times
correspond to actual higher rates of
production of CO, in the body.
What’s this color change all about? BTB is an “indicator solution” that changes
color when a certain gas is bubbled through it. Do you know which gas in your
breath makes BTB change color? For a hint, do the following:
D. Rinse the beaker and fill it again about 1/3 full with BTB.
Optional
E. Fill a 150 ml flask with water to about an inch below the end of
the glass tube. Have the l topper, glass tubing and hose ready
to put into this flask.
BTB
t ALKA Seltzer
F. Now work quickly. Add one alka-seltzer tablet to the water,
put the stopper tightly in place, and submerge the hose into the
beaker. Observe the BTB solution and record your observations.
Do you know what gas is formed by the alka-seltzer when it is dissolved in water?
It’s the same gas that’s used in soda pop to make it carbonated-carbon dioxide.
That’s the gas in your breath that you measure with BTB.
Food, Energy, and G r o w t h
a7
Lesson
10
Food, Energy, and Growth
TEACHER’S GUIDE
TG 37
G. Now, determine the amount of carbon dioxide in your breath by seeing
how long it will take to turn BTB solution from blue to yellow. Again, you
need to have a clock or watch with a second hand available. Rinse the beaker
and fill it with exactly 50 ml of BTB. Now, inhale deeply. Then, using the
straw, blow steadily into the BTB until the solution just turns yellow. In your
journal, record how long it took for the solution to change color. This is your
‘normal carbon dioxide rate.”
d
Part 3. Exercise and check your rates again!
Think for a minute about exercising vigorously, then.. .
1. Students might correctly predict that
the amount of CO, goes up during
exercise even if they hold the naive view
that oxygen magically changes into
carbon dioxide in the lungs.
You might want students to try to plan
this experiment in small groups.
1. Predict how your breathing rate, pulse rate, and“carbon dioxide
rate” will change during vigorous exercise. Give reasons for
your prediction.
$ ’
l!ll
A
After making this prediction, take a few minutes to try to plan an experiment to
test this prediction. Write out all the details of this experiment in your journal,
including the equipment you’ll need and the steps you’ll follow. If you think you
have a good experiment, check with your teacher before you proceed to do it.
***
If you aren’t sure about how to set up this kind of experiment, you can follow the
directions below:
1st: Exercise
2nd: Check and record your breathing rate and pulse rate
3rd: Check and record your “carbon dioxide rate”
d
H. Get your apparatus ready to teat your breath right after you exercise.
Use exactly 50 ml of BTB in your beaker to make an exact comparison with
your “normal carbon dioxide rate.”
I. Now, exercise vigorously by jogging in place for two minutes. Time yourself.
38
Michigan Department of Education
Lesson
10
TG 38
d
Michigan Department of Education
LJ
J. Immediately after you stop jogging, inhale deeply and start keeping
track of the time. Then using the straw, blow steadily into the test solution
until the solution just turns yellow. Record the time it took for the solution
to just turn yellow in your journal.
K. Count your breathing rate for 60 seconds and record this data in your
journal.
L. At the same time you’re counting your breathing rate, have a partner
count your pulse rate for 60 seconds and record this data too.
2. a) breathing rate up
pulse rate up
“carbon dioxide rate” is faster
b) more
2. a) What differences did you notice in the three indications of your body
rates before and after exercise: breathing rate, pulse rate, and carbon
dioxide rate? Was your prediction from #l confirmed?
b) If your breathing rate is higher, what does this mean about the amount
of oxygen you’re taking into your body?
c) What do you think it means that your pulse rate is different? Think
about food and oxygen when you answer this question.
d) Draw a conclusion from your BTB tests: Are you exhaling more or less
carbon dioxide after exercise?
e) What evidence do you have of this?
f) Here’s the clincher question: Where in the body do you think this
additional carbon dioxide must come from? (Want a hint? During your
jogging exercise, what specific parts of your body needed extra energy?)
iJ
3. Before going on to Lesson 2, think about the evidence you have just
gathered, and write a briefbeginningexplanation of what you think seems
to be happening inside your body when you use food during exercise.
So what’s actually going on in your body to produce carbon dioxide? What does
your body do with the oxygen you breathe? What’s actually going on to get the
energy out of food for your body to use?
We will use the evidence we’ve collected so far, along with some more evidence we’ll
collect in Lesson 2, to find good answers to these questions. We will take an imaginary
trip down into the cells to see what’s really going on.
Food. Energy, and Growth
3s
c) the heart is pumping blood faster
around your body, delivering
oxygen and digested food to the
cells
d) more
e) it took less time to turn BTB
yellow
from the muscles - more
specifically, from muscle cells. This is
a very important concept, one that
students routinely don’t master, that
carbon dioxide is produced in the cells
and travels back to the lungs and out of
the body. Students typically think that
carbon dioxide is simply exchanged for
oxygen in the lungs. If they can trace the
oxygen going to the cells and the carbon
dioxide coming back from the cells to
die lungs, then they are less likely to
hold on to the misconception.
3. If students say that cells (or muscles)
need food and oxygen when they do
work, and the cells (or muscles) release
carbon dioxide, they’ve got the idea for
this lesson. They don’t need a detailed
explanation of cellular respiration, since
that comes in the next lesson. This
lesson simply provides them with
empirical evidence that they’ll need to
understand cellular respiration.
Lesson
lo I
Food, Energy, and Growth
TEACHER’S GUIDE
TG 39
Lesson ll
*
NOW YOUR BODYACTUALLY
GETS ENERGY OUT OF FOOD
Have you ever heard the statement: “Your body burns food to get energy?” Have you
ever thought about what this means? Take some time to think about it now: What
connectiona can you see between burning paper or wood and what your body does
when you exercise? Share your thoughts with your classmates.
Key
Question
How does the energy in food become energy that
your body can use?
Since it is difficult to investigate in our own bodies how we might really “bum
food,” we will investigate it by first burning a sample of food outside of our bodies,
and then making a few comparisons with what happens to food inside our bodies.
You can burn a peanut or walnut as well
as this butter - all produce carbon
dioxide. But using the butter candle
rather than a flaming peanut sets up
question #3 on p. 41, which is important
to help establish the idea that this is a
chemical change. (Margarine does not
work well as a substitute for butter.)
The butter candle also produces water,
which can be seen easily by placing a
cold plastic plate over the candle and
noticing the moisture that condenses.
This is not done in this activity, nor is the
production of water discussed at length,
because it is difficult to establish some
evidence for stndcnts of water production
in the cells. The water we breathe out,
for example, is not necessarily produced
in cells during cellular respiration; we
arc constantly drinking water and there
is water all over our bodies, so there is
naturally water vapor in our lungs.
4% This: Build a butter candle
A. Cut about one inch off from the end of a stick of butter and place it in a Petri
dish. Shape the butter into a small mound.
B. Using a pencil or other sharp object, poke a hole into the top of the mound of butter.
The hole should go about halfway through the mound from top to bottom.
C. Insert a 1” to 2” piece of cotton string into the hole and secure the string by
gently pushing and then pinching the butter around it. Only the very end
should be exposed, like a candle wick.
D. Light the wick and observe your candle. Record your observations.
40
Michigan Department
of Education
Lesson Statement: Students make and a observe a burning butter candle, They compare
the reactants and products of this energy-producing process to the same process in their
Lesson
11
TG 40
own body,
Purpose: To develop an understanding of the process of cellular respiration by
comparing it to burning butter.
Approximate Time: 2 class periods
Michigan Department of Education
E. While the candle is still burning, test the air around it by pouring a little BTB into
LJ
the Petri dish around the base of the butter candle. Cover the candle and Petri
dish with a 250 ml beaker, so the spout on the beaker is under the BTB. Let it
continue until the flame goes out. Then swirl the Petri dish, candle and beaker
slightly and look for any color change in the BTB. Record your observations.
1. releases energy; produces carbon
dioxide.
2. stored in the butter. Some students
may suggest that the energy was in the
flame that lit the candle - see comment
below.
1. What evidence do you have that the burning butter candle is like whatever
is going on inside your body when you use food. Think about Lesson 1.
Describe your evidence in terms of energy and substances.
2. When the butter candle burned, it released light and heat-both forms of
energy. Where do you think that energy was before the butter burned?
3. a) When you watched the butter candle, you saw it burn and melt. Which
of these changes do you think caused the carbon dioxide to form?
b) Do you think that what happens to the butter you eat is a chemical or
physical change? Why?
4. What do you think would happen if you let the butter candle continue to
burn with the beaker over the Petri dish? Do you know what substance
in the air is needed for paper, wood, or even butter to burn?
LJ
So what might be going on inside your cells when you need
energy? What do we know so far? From Clusters 1 and 2, we
know that
l
Digested food goes to your cells.
l
Oxygen goes to your cells.
So far in Cluster 3, we know that more carbon dioxide comes out
of our body when we exercise, so can we conclude that
l
Carbon dioxide is produced in cells when food is used for
energy.
Also, from the difference between burning and melting, we know
that
l
Whatever is happening in your cells is a chemical process.
Food, Energy, andG
Growth
G
41
Where does the energy come from? Energy released by the butter,both in the candle and
inside one’s body, is stored as chemical energy in food-a type of potential energy. The energy
released is not produced by changing matter into energy. Instead, you can think of energy as
being “locked up” in the glucose when it is made by plants-this energy originally coming from
the sun-and unlocked in cellular respiration. Students may understand this from their earlier
studies of photosynthesis or energy flow in ecosystems.
But the concept of potential energy is still often vague. Sometimes students believe that the
energy they see in the candle simply came from the match that was used to light it. If this is what
(continued on next page)
Food, Energy, and Growth
TEACHER’S GUIDE
3. a) Burn
b) It’sinterestingtolistentostudents’
views on this. Allow them to debate it
for awhile. Ask them whether gas is
given off when other things melt, like
ice. We’re trying to establish the
important idea that this process of
releasing energy involves a chemical
change (actually many chemical
changes.) Melting is only a change in
state and, in fact, the butter absorbs
energy from the burning process as it
melts. Burning is a chemical process
that changes the butter into new chemical
substances.
4. Oxygen is needed. Eventually, the
oxygen under the beaker would all be
used up and the candle would go out.
As the candle burns under the beaker,
students may notice the level of BTB
inside the beaker going up. This is not
the crucial observation (the color of the
BTB, indicating released CO,, is) but
some students might ask about this. It is
because there is more oxygen used by
this chemical reaction than carbon
dioxide produced, reducing the number
of molecules inside the beaker, and
therefore reducing the pressure. The
outside air pushes up the water from the
outside.
rl
Lesson
II 11 II
el
TG41
Cellular respiration is a chemical
reaction-actually a series of complex
chemical reactions summarized by the
equation shown here-that essentially
rearrange the atoms of the reactant
substances (glucose and oxygen) to form
new substances (carbon dioxide and
water), and in this case, release energy.
Burning butter is a chemical reaction
which requires oxygen (so is burning
wax in a candle, or burning wood or
paper.)
No matter is lost in this or any chemical
reaction: the mass of water and carbon
dioxide produced is exactly the same as
the mass of glucose and oxygen that
react together. You can see this by
noticing that the equation is balanced:
all the atoms that go into the reaction
come out again. The energy stored in
the original molecules is released for
use in cell processes.
You may wish to discuss with students
what happens when one is deprived of
oxygen, as in carbon monoxide
poisoning. Actually, death is caused
because cells are not getting the oxygen
they need. The first cells to be effected
are usually brain cells and people become
light-headed and pass out very quickly.
Cells are deprived of oxygen because
carbon monoxide will attach itself to the
hemoglobin of the red blood cells 250
times faster than oxygen will. Also, it
attaches more strongly than oxygen so it
Building
on your
conclusions
Yes, a very complex set of chemical reactions in going on in cells
that release the stored energy from glucose. Oxygen is needed to
make these reactions occur, and carbon dioxide (and also water)
is what's left after the reactions occur. To simplify these reactions,
scientists write one equation:
C$I,O, + 6 0 , F
SH,O
t
6C0, releasing
glucose t oxygen F water t carbon
vapor
dioxide
What this looks like in
a cell is this:
The glucose and oxygenmolecules react, and the stored energy is released! The
chemical reaction produces water and carbon dioxide, which leave the cell.
This process that cells use to get energy from food is called cellular respiration.
It is the reason why you can’t live more than a few minutes if you atop breathing.
If cells can’t get oxygen, they can’t get the energy out of food, and they die very
quickly. What would happen to you if your brain cells couldn’t get oxygen?
***
does not exchange with oxygen. As a
result, the oxygen-carrying capacity of
blood is drastically reduced and cells are
What’s the difference between
a burning butter candle
and what goes on in your cells?
no longer getting the oxygen they needthus dying of asphyxiation.
42
Lesson
11
TG 42
Michigan Department
of Education
many of your students think, then point out to them that the candle burns much longer than the
match, indicating that there must be some additional energy (lots, actually) in the butter itself.
If they believe that it is only the wick that is burning, have them try burning a wick by itself along
side the candle: Which burns longer?
You may need to use an analogy for chemical energy changing into heat or light energy, such
as in a light bulb or electric stove, where electrical energy is changed into heat and light energy;
or in a fan, where electrical energy is changed into mechanical energy.
Michigan Department of Education
Cellular respiration is very similar to the process of producing energy in the form
of heat and light when you burn a marshmallow or butter: Both require
oxygen; both release energy stored in the food, both produce carbon
dioxide and water.
There is a difference though: Your body cannot bum food with a flame, and it
doesn’t need or produce light energy. But it does need and produce heat energy,
which is used to keep your body warm-much warmer (usually) than the
surrounding temperature of the air.
Also, burning butter provides too much energy too fast. Your body needs energy
all of the time in much smaller, controlled amounts. H OW does it do this? How
does cellular respiration release small amounts of energy? By using only small
amounts of glucose and oxygen?
Yes, there’s not nearly as much glucose in any cell as there is butter in a
butter candle. But there’s more to this story.
Cells are very complicated. Inside cells, the
energy released from glucose isn’t used up
right away. Most of the energy goes into
many special molecules in each cell called
ATP molecules. Each of the ATP molecules
can store the energy from glucose in very
small usable quantities-unlike a candle,
which burns quickly and releases energy
quickly. These energy-rich ATP molecules
travel all over the cell, supplying energy
when needed by cells, for motion in muscle
cells, for light in the light-producing cells of
the firefly, or for electrical signals in brain
cells.
The chemical formula for fat in the
butter candle is different from the formula for glucose. A typical fat present
in butter is glyceryl tristearate and the
chemical formula is C&I&,0,. Notice
that both glucose and the fat contain
only carbon, hydrogen and oxygen. Both
bum to produce carbon dioxide and
water, releasing energy.
In our bodies, fats need to be converted
to glucose before they can be used in
cells for energy.
The heat produced by the process of
cellular respiration is used to keep our
body temperature at 98.6F (37°C.) As
warm-blooded organisms, our body
temperature stays constant and we
maintain a stable internal equilibrium.
The reason we perspire when we exercise
vigorously is to help get rid of excess
heat from the additional cellular
respiration. As water evaporates from
our skin, it takes with it some of the
excess heat being produced, thus cooling
our skin.
ii)
TqT h'1s: In your journal, draw an outline picture of a human body,
large enough to fill an entire piece of paper. Draw in a cell in a muscle in the
forearm. Show in your drawing how food gets from the mouth to the cell. Show
how oxygen gets from the mouth or nose to the cell. Show how carbon dioxide gets
out of the body.
***
Extending
what you
Know
Why do you get tired when you exercise? Why do you sometimes
get cramps if you exercise too long and too vigorously?
43
Food, Energy, and Growth
We are deliberately not going into too much complexity with this discussion of the chemical
process of cellular respiration. We have chosen instead to promote students’ depth of
understanding of cell processes by putting them in the contexts of 1) breathing and exercise
(Where does the carbon dioxide we exhale come from? Why do we breathe more quickly
when we exercise); 2) growth (Where does the new material come from when we grow?
What’s theconnectionbetween growing and eating well?); and 3) weightgainand weightloss
(Why does exercise help us lose weight?) We consider these real-world contexts and these
questions to be the substance of scientific literacy, rather than the complexity of cellular
(con't on next page)
Food, Energy, and Growth
TEACHER’S GUIDE
It might be interesting to allow students
to ponder these questions for several
minutes before continuing to read the
page. Let them voice their ideas about
why exercise makes one tired. You may
want to press them to talk about food
and oxygen in their explanations. and
what the body needs food and oxygen
for.
I-l;i
Lesson
11
TG 43
If you said you get tired when you exercise because you run out of food in your
body, that would be a good guess, but most people have extra food-energy-rich
fat-stored in their bodies just in case their glucose gets used up. (Thisisoneway
that exercise helps people lose weight, by using extra fat.)
What happens if
your breathing
can't keep up
with your
Other “real-world” contexts of
respiration include yeast in breadmaking (as yeast consumes the sugar in
the dough, its cellular respiration
produces carbon dioxide, making
bubbles that make the dough rise) and
fermentation.
But your body can’t store extra oxygen. You get whatever
you ueed by breathing. When you exercise, do you need more
oxygen? Well, if your muscles need more energy to move fast
during exercise, then you’ll need more oxygen to release that
energy from glucose. But if your muscle cells need energy
faster than oxygen can be supplied to the cells by breathing,
what happens?
Your muscle cells can’t use glucose the same way if they don’t have 6 oxygen
molecules for every glucose molecule. In&ad, a different chemical reaction
takes place, one that releases much less energy than the cellular respiration
reaction with 6 oxygen molecules does. And this different chemical reaction also
produces an additional by-product (just like when a candle is short of oxygen, it
can produce more smoke.) Because this by-product is produced faster than your
blood can carry it away, it begins to build up in your muscles, causing pain and
fatigue. That’s why your muscles ache and you get cramps!
The by-product is lactic acid, which
changes the pH in the muscles and keeps
the muscle fibers from relaxing after
they contract.
Some forms of exercise automatically rest your muscles after each
time you use them. Cross-country skiingir one example. Duringthe
normal motion of push-glide, you use your muscles when you push.
During this time, your cells release and use energy. Then you rest the
muscles while you glide. This allows your body to continue to supply
enough oxygen for the amount of energy required. Normal crosscountry skiing along flat ground is good exercise for your heart, but
doesn’t necessarily wear you out!
5. Answers will vary but the following
key points should be included:
food supplies the substances needed
by the cells for making new materials
and for producing energy. (Be sure
students include both uses.)
glucose and oxygen are chemically
changed in cells intocarbon dioxide and
water vapor, releasing energy.
the process is called cellular
respiration.
l
l
l
5. Please explain in your own words why you need to eat. Don’t forget to talk
about cells in your explanation.
6. The oxygen from the air you breathe
is carried to cells where it is used to
release the energy from glucose.
6. What happens to the air you breathe in?
7. Where does the carbon dioxide in your exhaled breath come from?
7. It comes from all the cells of the
body. It is produced by the cells when
glucose and oxygen react chemically to
form carbon dioxide and water, releasing
On to the next lesson...
44
energy.
Michigan Department
L
q
Lesson
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TG44
processes, and we hope that theknowlegde students construct as they search for answers to these
questions will be retained by more students into their futures.
Students’ conception of respiration:
If students have heard the word “‘respiration”
before, they generally think of it only as breathing. This is where the common confusion about
oxygen turning into carbon dioxide in the lungs comes from. With this naive view of respiration,
they miss the essential connection between oxygen and food, and that a chemical reaction is
needed for the production of carbon dioxide.
Michigan Department of Education
Lesson 12
GROWING
Most people know that you need to eat well to grow well. But just what does this
mean? And how does food help a person grow?
Throughout this unit we’ve said that food does two important things for living
organisms (yes, not only humans, but dogs, cats, insects, bacteria, even plants!)
It provides the energy they need for all of their body’s activities, and it provides
the raw materials needed for growing and repairing damaged body parts. But
what does it mean to say that food provides raw materials for growing7
1o
help
~~~~ion
a
teenager
This key question, which will be
examined as this lesson continues,
get
How does food help a lizard regenerate a tail that
assumes that students realize that when
they grow, they actually have more
material in their body than before-it’s
not a case of getting larger like a balloon
expanding. The questions that follow
the key questions are intended to help
students recognize this.
How does food help a plant increase its size?
As you grow between the ages of 5 and 15,
you get much bigger and your weight increases.
Your bones get longer.
Your muscles get longer.
Do they just stretch?
13
The important idea for this lesson is that
As your bones and muscles get longer, you need more skin to cover them. Your
body needs more blood to move food and oxygen to all of its cells.
some material from food gets
incorporated into bodies (cells) as we
grow.
Does your skin just stretch to cover your larger body? Does your blood just “thin
out” to move over longer distances?
Let’s think about one muscle as it grows:
As it gets longer, does it weigh more?
Is there more muscle material in it if it weighs more?
Do you think that your body adds more muscle material to the growing muscle?
Where do you think that extra muscle material comes from?
***
Yes, it comes from food. But the tricky problem is: Since you don’t eat human
muscle material, how do you get it? How do the animal and plant parts you
eat become part of you? How can food materials that come from animals and
Food, Energy, and Growth
46
Lesson Statement: Students go back to the model of the digestive system they made
in Cluster 2 and use the amino acids from digested foods to make new protein. They make
different arrangements of various numbers of objects to simulate they sythensis of
proteins from amino acids.
Purpose: To understand how our bodies grow by adding new materials to cells.
Approximate Time: I or 2 class periods
Food, Energy, and Growth
TEACHER’S GUIDE
Lesson
12
TG 45
5
0
YouWiIl Need:
l
l
model from Cluster 2, Lesson 8
“molecules” of protein, fat, and carbohydrate
’ pine
Get out the model of the human digestive and circulatory systems you made in
Cluster 2. Find the piece of different shaped paper that represent each of the
basic components of food-the carbohydrates, the proteins, and the fats.
A. Place these pieces in the small intestine. They will represent, say, some
broccoli and hamburger you just ate (plant and animal parts.)
B. Then pretend that the food is being digested: Separate the food particles into
their digested products, showing that proteins are digested into
carbohydrates are digested into _ and fats are digested into -1
C. Move these digested particles through the wall of the small inteetine into the
blood stream, and give them a ride to, say, a muscle cell in your forearm.
What happens to them in the cell?
This is the big question. ‘We already know what happens to glucose in the cell
(what?) But what happens to amino acids?
Think this through for a minute. If your body needs new material to add to muscles
as they grow, but you can’t add the cow muscle materials in hamburger to your own
muscles, where could this new material come from? From these amino acids? Yes.
Just as proteins are broken down into amino acids, amino acids can be built back
up into new proteins, the exact ones you need to make new muscle material!
Your cells are tiny architects, building new muscle structures from the raw
materials-the building blocks-of amino acids.
D. Use the amino acid pieces of paper in your model to build new proteins by
taping them together in new ways. In your model, these new proteins can be
thought of as new muscle material.
46
Lesson
12
TG 46
Michigan Department of Education
The role of vitamins and minerals in growth: Vitamins and minerals are essential for
making the chemical reactions occur that combine amino acids into new proteins. They are not
incorporated into the new proteins, but are co-factors with enzymes to make these reactions
occur. Vitamins cannot be produced by the body, so they have to be eaten; and some are not
stored in the body for very long, so they have to be eaten every day. Certain minerals have other
functions also, such as calcium in the production of bone matter, iron in the production of blood
hemoglobin, and phosphorus for nerve firings.
Michigan Department of Education
1. Amino acids from our digested food
are put together in cells to make new
blood cells.
individual amino acids
arc j o i n e d in wpacial
combinations to make all
the proteins you need
picture we’re constructing is fantastic! Cells building new muscle materialsusing the food we eat, digested into amino acids, to build new proteins that
become part of the cell. As the cells get larger with this new material, they divide,
making new muscle cells, and the muscle gets larger! Each cell is its own
architect, building just the kinds of proteins it needs to make new cells.
This
2. Same as blood. You might point out
to students that since skin is different
from blood, it must be made of different
proteins, which must be made from
different combinations of amino acids.
Using the ideas we’ve just considered, try to answer the following questions.
1. How do you think new blood is made?
2.
How do you think new skin is made?
***
Optional
experiment
One of the difficult questions that comes up with the picture we’re
constructing is this: How can your body make so many different
kinds of proteins, for all of the different parts of all of the different
cells your body needs?
E. Nature actually has 20 different amino acids to work with. To see how many
different proteins these 20 might make, start to build proteins yourself with
just three different amino acids. Arrange them in as many different
combinations as you can, using each only once. Each combination represents
a new protein. How many combinations can you come up with? (This is like
taking 3 different letters of the alphabet, and arranging them in as many
different words as you can, where the words might come from any different
language.1
F. Add a fourth, different amino acid to the three you already have. Begin
arranging these four to make different proteins. How many combinations
could you make with 4 different amino acids?
Food, Energy, and Growth
E. You could make 3 different
combinations: ABC, ACB, and BAC.
This assumes that ABC and CBA are the
same protein, just turned up-side-down.
Mathematically, the number of
combinations is represented by 3!/2,
which is (3 x 2 x 1)/2 = 6/2 = 3.
With 4 different amino acids, you could
make 4 !/2 combinations, or 12:
ABCD,ABDC,ACBD,ACDB,ADBC,
ADCB, BACD, BADC, BCAD, BDAC,
CABD, CBAD
47
sl
Lesson
12
Food, Energy, and Growth
TEACHER’S GUIDE
TG47
2O!/2 =
G. How many different proteins could be made from various combinations of the
20 amino acids? Could you use a calculator to make some kind of
approximation? Try it!
Actually, scientists have analyzed many different proteins to find out which
amino acid building block.6 they are made of. They have found that protein
molecules consists of anywhere from 50 to more than 10,000 amino acid
molecules, where each amino acid can be used more than once--in fact, they can
be used numerous times. Think that gives nature enough combinations to play
with?
All of the proteins that make up our body parts are made by our cells-tiny little
factories using amino acids from digested food as raw materials. When you grow,
your cells make new proteins, and add them to their own internal structures. As
the cell gets larger, it divides and forms new cells. More and more cells are added
to your muscles (skin, blood, etc.) as you grow. Your new cells come from the food
you eat!
As each cell m a k e s n e w
proteins they a r e added to
the c e l l As the cell g e t s
3. New proteins are made from the
amino acids of our digested food. When
the cell is big enough, it divides and
,
forms new muscle cells.
all over. This is how you grow!
4. Vegetable and animal proteins in
food are digested into amino acids,
which are delivered to the cells by the
blood. They are assembled into new
proteins inside the cells. Glucose from
our food provides the energy needed for
all of these growth processes.
5. This process is exactly the same in
animals as in humans. In this case, the
new proteins are formed in cells in the
tail stump.
To review:
3. Explain, as completely as you can, what happens to a musclewhen you grow.
4. How does food help a teenager get taller?
5. How does food help a lizard regenerate a tail that gets tom off?
6. How does food help a plant increase its size?
6. Plants can make their own amino
acids from the glucose they make in
photosynthesis and the minerals they
take in from the soil. Their growth
process is essentially the same, then, as
in animals.
48
Lesson
12
TG 48
Michigan Department of Education
What happens to extra material from the food you eat that is not needed for energy,
or that is not used for growing or repairing your body? Your body makes fat cells
out of it! Extra food you eat that isn’t used for energy and isn’t used for new materials is stored
by your body as fat cells for later u.se. Some animals do this to prepare for winter, when food
is very scarce. Plants store extra food as starch (not fat) so they can live when there’s not enough
sunlight to make their own food. (People also store extra carbohydrates as starch for short term
Use.)
Michigan Department of Education
WEIGHT GAIN AND
WEIGHT LOSS
Lesson 13
44 tt
All living things undergo continuous change during their brief span of life on
earth. Fish get bigger, trees add new branches, crayfish regenerate damaged or
lost parts, and people increase in size. In this lesson, you will use what you
learned earlier in this cluster to help you understand the balance in your body
between what goes in and what comes out.
P
3
Questions
Allow students to speculate about these
key questions, without providing
answers at this point in the lesson.
Why does the food you eat make you grow and
gain weight sometimes but not other times?
What role does exercise play in weight gain and
weight loss?
Imagine two identical twins, Emily and Felicia. Each weighs 120 pounds. Emily
is thirsty and so she drinks a pound (about a pint) of water. Feliciais very hungry
so she eats a pound of spaghetti. For the purposes of this activity, consider all
other food, water and activities of Emily and Felicia to be exactly the same unless
indicated otherwise. Here is what happens to the weights of the two girls:
Emily (wafer)
Felicia (spaghetti)
Weight before
eating or drinking
120 lb.
120 lb.
Weight right after
Weight after
In answering questions l-4, students are
eating or drinking
121 lb.
121 lb.
one day
120 lb.
120.2 lb.
asked to do more than compare the effects
of eating and drinking. They should
speculate about what actually happens
to food and water inside the girls’ bodies.
Most answers will probably be
incomplete at this point. Note where
students difficulties are.
Do you notice any pattern here? Both girls gained weight right away but lost
mostofthatweightwithinaday. Felicia, though, didn’t lose quite all of the weight
she had gained.
1. Why do you think Emily did not show any weight gain after one day?
Explain what Emily’s body did with the water.
2. Why do you think Felicia showed a slight weight gain after one day?
Explain what Felicia’s body did with the spaghetti.
On a different day, Emily and Felicia both decided that they want to lose weight.
Emily sat in a sauna for half an hour. She perspired a lot. Felicia ran for half
an hour. She perspired a lot too. Here is what happened to their weights:
Food, Energy, andGrowth
49
Lesson Statement: Students analyze several hypothetical cases of weight gain and
weightlossanddecidewhatfactorscausedeacheffect. They make predictions for specific
situations and write a plan by which they can attain their own goals. They explore the
weight balance of all things that go into one’s body and come out.
Purpose: To help students understand weight gain and weight loss both with regard to
short term effects and Iong term effects.
Approximate Time: 2 class periods
Food, Energy, and Growth
TEACHER’S GUIDE
1. Emily’s body used the water to help
remove waste products through urine
and feces; she lost the water in these
ways over the long term, and returned to
her original weight.
2. Felicia’s body used some of the
spaghetti (the protein) to build new body
cells, adding to her weight. Most of the
spaghetti, however, was used forenergy,
and the products of cellular respiration
(carbon dioxideand water) were exhaled
and excreted.
131
Lesson
13
TG49
3. Mostlybydrinkingwatertoreplenish
what they lost through perspirationour bodies demand this from us after we
exercise!
3. How did the two girls gain back the weight they had lost?
4. Notice that Felicia didn’t quite gain all her weight back. Why? What
happened to that weight?
Both girls lost weight shortly after their activities by losing
mostly water due to perspiration. They gained it back by
drinking. Felicia, though, also used some stored food for energy
needed for running. Through cellular respiration, it changed into
water and carbon dioxide, and left her body, reducing her weight.
4. She needed extra energy to make her
body work faster than normal, so she
used some of her stored body fat for that
energy. It was changed to carbon dioxide
and water, and exhaled. She actually
lost weight by exhaling CO,!
In general, you can do many different things that can cause you
to gain or lose weight. Some of them make you gain or lose weight
only in the short term. Others cause long term or permanent
weight gain or loss. Let’s try to sort out which activities have
which sorts of effects.
5. Look at the activities listed in the table below. Think about what things cause
only short-term weight gain or loss and what things cause long term weight
gain or loss. Thencopythefollowingtableandfillineachspacewithoneofthe
following weight gain, weight loss, no effect or not sure.
5. (see table)
6. Long term weight gain: eating food
that helps build new cells (proteins) or
that can be stored as body fat. This food
intake has to be beyond what the body
requires for energy.
Long term weight loss: exercise that
uses stored body fat for its energy
content, changing it into carbon dioxide
and water. The carbon dioxide is
exhaled, losing its weight.
b. ones that only involve water intake
or loss
I
[weight loss or no effect]
[no effect]
6. a) Study your answers and make a statement about what sorts of
activities lead to long term weight gain or weight loss.
bb
) What sorts of activities have no long term effect?
50
Michigan Department of Education
-
Lesson
13
TG 50
Calories: We deliberately have not talked about calories in this lesson, allowing the idea of
calories to come up as a question from students instead. Many students are familiar with the idea
of “counting calories” for dieting, or have seen the caloric value of a serving of food on package
labeling. “Calorie” (with a capital C) is a common unit of energy that refers to the amount of
energy released from the food when it is oxidized in the body-one Calorie is equal to the amount
of energy needed to raise one kilogram of water one degree Celsius. In dieting, people often try
to restrict the amount of calories (Calories) they eat, which is not the same, of course, as
restricting only the quantity of food eaten, since some foods have more calories per ounce (or
Michigan Department of Education
7. How can you explain long-term weight gain in terms of how our bodies use
food? Use the concepts of digestion and cellular respiration in your
answer.
8. Explain, in terms of energy, how you can control how much long-term
weight you gain or lose?
9. Why does eating sugar result in weight gain if it is stored as fat, but not
if it is used in cellular respiration.
10. Tell what kind of diet would be good for each of the following situations.
Explain how you made your choice.
a) You are a body builder and want to add muscle to your body.
b) You want to gain weight.
c) You are planning an expedition to the Arctic and want to get your body
ready for the trip.
d) What does a bear need to eat as it prepares for hibernation?
Body fat is not a bad thing. If you were exploring in the Arctic, you might have
to go without food for several days. Excess food stored by your body as fat can
be converted to glucose and used for energy when your body needs it. In times
past, people might use body fat if crops failed or hunting was bad; body fat was
important. In those situations, some people without some stored energy would
weaken and perhaps die. Today, for people who never go hungry, the excess fat
their bodies store is no longer useful. Because fat can cause serious health
problems such as heart disease and high blood pressure, we need to keep our
bodies from storing too much fat.
***
11. What do you want for yourself-weight gain, weight loss or just maintain
your current weight? Write a plan that will help you achieve your goal.
Tell why you think your plan will work.
Food, Energy, and Growth
51
gram) than others. Generally foods high in calories (by weight) contribute more to body fat than
those low in calories. But energy is needed by all people, even if they are dieting, so they have
to maintain some minimal caloric intake-this is why bulimia or other forms of not eating are
dangerous: Without any food, our bodies have no energy and no materials for growth and repair.
New dietary guidelines recognize that foods high in saturated fats contribute more to body fat
(and heart disease) than those of similar calorie content that are low in saturated fats.
Food, Energy, and Growth
TEACHER’S GUIDE
7. Digested food(imarily amino acids
and fatty acids) can be used for growth
or for storage of fat; both result in weight
gain. If digested food is used for repair
or for cellular respiration, there will not
be any long-term effect.
8. If you want to gain weight, take in
more food for energy than what your
bodyneeds. Itwillbestoredasbodyfat,
adding to your weight.
If your body needs more energy than
what’s stored in the food you eat every
day, it will use stored body fat for that
extra energy, changing it to carbon
dioxide and water, and exhaling the
carbon dioxide.
9. When it is stored as fat, it adds to the
weight of the body. When it is used in
cellular respiration, it is changed into
carbon dioxide and water vapor, and
expelled from the body.
10. a) A diet rich in protein will provide
aminoacidsneededforbuildingmuscle.
b) A diet high in carbohydrates and
especially fat will provide the excess
needed to gain weight.
c) Fats have twice as much available
energy as carbohydrates (that’s why they
taste so good.) Eat lots of carbohydrates
and fat to store up extra energy.
d) Lotsoffattostoreupextraenergy
for the body to keep warm and function
during the long winter (Although bears
don’t actually hibernate-their body
temperature does not drop significantly-they are much less active
because food is much less available. In
the same way, plants store food in the
form of starch in the roots for use during
the spring, before their leaves begin
producing their own food.)
11. Answers vary
s
Lesson
13
TG51
Nature is a meticulous bookkeeper. Nothing is ever lost or gone. It just changes
into new or different forms. This is one of the most fundamental laws of nature:
In chemical reactions like cellular respiration, matter can neither be created or
destroyed. It can be changed only from one
to another. In the case of cellular
respiration, matter is changed from one form (glucose and oxygen) into another form
(carbon dioxide and water.)
But you can keep track of the amount of matter, even if it changes
form. Every ounce of food you put into your mouth, and every ounce
of air you breathe into your body through your lungs, has to be
accounted for in either the weight you gain or the substances you
release from your body (including when you g o to the bathroom,
when you breathe out oxygen and carbon dioxide, and when you
perspire.)
Every
Ounce
12. Rewrite the following statements in yourjournal, and fill in the blanks
with one of the following: equals (=), is greater than (>), is less than (<)
12. =
>
<
If your weight stays the same:
ALL THE STUFF
ALL THE STUFF
THAT GOES IN 0 THAT COMES OUT
So, if your weight increases:
ALL THE STUFF
ALL THE STUFF
THAT GOES IN c l THAT COMES OUT
So, if your weight decreases:
ALL THE STUFF
ALL THE STUFF
THAT GOES IN 0 THAT COMES OUT
The idea that the mass of the food we eat
has to be conserved is especially difficult
for many students. They don’t always
easily recognize that the amount of
substance we excrete (including water
vapor, perspiration, carbon dioxide, and
excrement) is less than the amount we
consume and breathe in, by just the
amount that is used to build new cells or
stored as fat.
We can actually keep what bookkeepers call a "balancesheet”of the matter that goes
into your body and the matter, that comesout. Start bydrawingachartsimilarto the
one on the next page (make a copy in your journal, don’t write in this book!) Then
follow what goes in and what cornea out during one day of your life.
Say you weigh yourself before breakfast and weigh 155 lbs. Then you eat a bowl
of cereal with a cut-up banana and a glass of orange juice. It weighs 1.2 pounds.
Record this on your balance sheet (as shown in the example.)
Later in the morning, you go to the bathroom. This is only liquid waste, and it
weighs 0.3 pounds. Enter it on the third line in the appropriate column. Keep
track of how your weight is changing through each of these activities.
52
Michigan Department of Education
Weight loss during exercise: What is it that's actually lost when weexercisethataccounts
L
Lesson
13
TG 52
for long-term weight loss? It’s not the fluids we lose from perspiration, because our bodies
demand us to drink water after exercise, to replenish the lost water. It’s not the heat energy that
radiates away from our bodies when we exercise, because heat energy has no mass (nor is matter
being converted to energy.) It’s the carbon dioxide, produced by cellular respiration of
carbohydrates and stored fats, that leaves our bodies through our breath. This is why exhaled
air has more mass than inhaled air, because of the extra carbon dioxide, which has more mass
per liter than oxygen. When we store body fat from eating foods, we’re gaining weight; when
we use stored body fat for extra energy during exercise, we are changing it into carbon dioxide
Michigan Department of Education
Materials In
beginning weight
breakfast
bathroom
Materials Out
Here are the calculations For inhaled air:
nitrogen molecular weight 28 g/mole x
79.02% (.7902) = 22.126 g/mole of air
oxygen molecular weight 32 g/mole x
.2095 = 6.704 g/mole of air
carbon dioxide mol. weight 44 g/mole x
.0003 = .0132 g/mole of air
Add the three together = 28.843 grams
total per mole of inhaled air
Weight
155 Ibs.
1.2 Ibs.
28.843 g/mole x 1 mole/24.5 1 (room
temp, 1 atm) x 5 liters/breath = 0.589 g/
breath inhaled air
Let’s say you also go to the bathroom again later in the morning, and this
time the liquid and solid waste together weighs 0.8 pounds. Record that
in the appropriate column of the fourth line. (Is excretion “materials out”
or ‘materials in?“)
What else goes in and out of your body besides food and excretion?
Your breathing takes in air, and when you exhale, you lose air. Can we figure
out how much a lungful of inhaled air weighs, and a lungful of exhaled air?
Using
Mathematics
How is the air that you breathe in different from the air you exhale?
The air you exhale has more carbon dioxide in it from cellular
respiration. Inhaled air is 20.95% oxygen, 0.03% carbon dioxide,
and 79.02% nitrogen (with a little bit of argon and some other
gases.) Exhaled air is 15.8% oxygen, 4.0% carbon dioxide, and
80.2% nitrogen (and small amounts of other gases.) Gases don’t
weigh much, but over a 24 hour period, especially if you exercise
and increase the rate of producing carbon dioxide, you wind up
breathing out measurably more weight (in gases) than you breathe
in. How much more?
You can figure this out with some math-just arithmetic, nothing
fancy. An average lungful of air (about 0.5 liters) that you breathe
in weights 0.589 grams. If you breathe 14 times per minute (and
there are 454 grams in 1 pound), how many pounds of air do you
inhale in the moming(say 5 hours)? Add this to your balance sheet,
in the appropriate column.
An average lungful of air (0.5 liters) that you breathe out weights
0.597 grams. Again, if you breathe 14 times per minute (and there
are 454 grams in 1 pound), how many pounds of air do you exhale
in the morning (5 hrs.)? Add this amount to your ledger, too.
Food, Energy, and Growth
53
and water, and releasing the carbon dioxide. The increased pace of cellular respiration during
exercise generally requires the use of stored body fat (which can be converted into glucose),
unless the person eats a big meal first. People who are deliberately trying to lose weight by
exercise usually restrict the amount of food they eat so that they will draw on stored body fat
during the exercise, thereby changing it into carbon dioxide and water and releasing the carbon
dioxide. In this chemical reaction, mass is conserved (the mass of glucose and oxygen equals
the mass of carbon dioxide and water as the reaction takes place in the cell) but our body weight
decreases when we exhale the carbon dioxide.
(continued on next page)
Food, Energy, and Growth
TEACHER’S GUIDE
0.589 g/breath inhaled air x 14 breaths/
min. x 60 min/hr x 5 hr x 1 lb./454 g =
5.449 lbs. of air inhaled in 5 hrs.
Similar calculations for exhaled air,
using the other percentages, yield 5.523
lbs. of air exhaled in 5 hrs.
To calculate inhaled & exhaled air for 6
hrs. (one afternoon) or 13 hours (from 6
p.m. to 7 am.) - used on next page divide the figures above by 5 to get
weight per hour, then multiply by 6 or 13
as needed.
(When we talk about “weight” of air, we
are really using the common units of
pounds to refer to a mass equivalent.
The actual weight of air-as measured
on a scale-is less than these figures
because of bouyancy. Once the air is
dissolved in body fluids, its mass and
weight are equivalent.)
Another approach to these calculations
is by using the fact that fat contains
9 calories of energy per gram (where
carbohydratesandproteinscontainabout
4 cal/g.) For every 9 calories of energy
you use exercising, you could be
“burning off’ 1 gram of fat. 45 grams is
about .1 lb.
Lesson
13
If you don’t exercise, you will not find much difference between what you breathe
in and what you breathe out in a day. Exercising speeds up your breathing rate
(as you know from Lesson 10). The difference becomes significant: you lose more
weight (in the form of carbon dioxide) than you take in. When Felicia ran for a
half-hour, she had a long-term weight loss of 0.1 lb. This was the carbon dioxide
she lost from cellular respiration of stored body fat,
excretion
I
I 0.3
I
I
Then record these other activities during your day, making sure to get them in
the right columns:
J
exercise
I
I 2.0
So say you exercised vigorously for a half-hour in the morning by playing
basketball. You lose 2 lbs, mostly from perspiration. Record this weight loss.
Then you immediately drank water from the drinking fountain: Record 1.9 lbs.
of water added to your body. Then you went to the bathroom around 11: Record
excretion of urine, 0.3 lbs.
I
lunch
bathroom after lunch
air in during p.m.
air out during p.m.
more exercise in school
drinking liquid
liquid and solid waste
a bike ride
drinking liquid
1.4 lbs. (turkey sandwich, fruit, milk, cookie)
0.3 lbs.
6.539 lbs. (for 6 hours)
6.628 lbs.
O.llbs.lostofcarbondioxide& 1.91bs.perspiration
1.9 lbs.
0.8 lbs.
0.05 lbs. lost of CO, & 0.6 lbs. perspiration
0.6 lbs.
dinner
bathroom
air in during night
air out during night
move some boxes
drinking liquid
bathroom before bed
urine when you wake up
1.6 lbs. (you liked it!)
0.3 lbs.
14.167 lbs. (for 13 hours)
14.360 lbs.
0.04 lbs. of CO, (light exercise) & 0.5 lbs. perspir.
0.5 lbs.
0.8 lbs.
0.6 lbs.
.
9 .
B_
13. Down by .746 lbs. (see spreadsheet
above)
13. After you fill in the entire balance sheet, has this person’s weight
gone up or down over this 24 hour period?
14. Probably the person will gain weight,
although it is hard to tell by looking only
at one day, since less than 2 cups of milk
would throw the balance in the other
14. If this person continues to eat like this and exercise like this, what
will happen to his (or her) weight?
direction.
54
Michigan Department of Education
The effect of exhaling carbon dioxide is relatively small, as shown by the calculations. Larger
weight loss by people who arc on a regular exercise routine may occur as their general hunger
or desire for food is diminished by the exercise routine.
Lesson
13
-A
TG 54
Michigan Department of Education
15. If weight was lost, less food was
taken into the body, and/or stored fat
was used for energy.
15. How might this person’s day have been different if he or she lost a
pound and wound up at 154 pounds after this 24-hour period? (Talk
about his or her food intake and exercise during the day.)
16. How might this person’s day have been different if he or she gained a
pound and wound up at 156 pounds after this 24-hour period? (Talk
about food, exercise, and growth in your answer.)
16. If weight was gained, more food was
taken into the body, and/or the person
became less active, utilizing less of their
stored body fat.
If your class chooses to do the next cluster, you will take a close look at several
different diets, including your own, and see if you’re eating well-if all the
nutrients necessary for energy and for growth and repair are present. You will
also look at the diets of several other cultures to see how they meet all of their
dietary needs.
If your class decides not to do the next cluster, you will still be able to look at,
think about, and make good decisions about what you eat. You now know why
it’s important to eat certain foods, and what happens to those foods inside your
body. You know what foods give you energy, and which help you grow and keep
all your cells in good repair.
And you are now better
prepared to think
critically about food
and health news and
comments you hear on
TV and read in the
paper. Keep your ears
and eyes open: Good
advice about eating
well is all around usand so is the good food!
Food, Energy, and Growth
55
Lesson
13
Food, Energy, and Growth
TEACHER’S GUIDE
TG 55
TG 56
Michigan Department of Education
Laboratory Background Information
for Cluster 4
Lesson 14 DIET AND NUTRITION:
WHATDO YOU EAT?
Many students have only very general knowledge about foods that are good
for them and those that are not. They have little or no knowledge about what
constitutes a balanced diet. In this activity, they will use the most recent
information about healthy diets from the U.S. Department of Agriculture to
analyze 3 diets-one that could use a lot of improvement, one that is quite
healthy and their own. They will come up with suggestions on how they could
make theirs healthier.
MATERIALS
3 blank “food pyramid” charts for recording data (in appendix), one marked
Marta’s diet before food unit, one marked Marta’s diet after food unit, and one
for student’s own diet. It will help studentskeep track of which is which if they
are copied on different color paper. Also, chart of protein, carbohydrate, and
fat content of various foods (in appendix).
J
If you want to show relative amounts of foods by “serving size," as indicated
on p. 56, you will also need bran flakes, a bowl, peanut butter, and 2 slices of
bread (maybe some jelly too, in case somebody wants a snack.)
PITFALLS AND CAUTIONS
1. It will be necessary to estimate number of servings, grams of fat, etc. based
on information in the margins of the “Eating Right Pyramid,” but it should
still be possible to come up with a pretty good estimate of how healthy a diet
is.
2. Whenever possible, students should keep the package information as this
will help greatly in analyzing the diet.
3. New regulations on labelling from the Food & Drug Administration, which
are just beginning to go into effect and will be phased in over the next several
years, should be very helpful in the future for those who are serious about
eating healthy diets.
Lesson 15 DIET AND NUTRITION:
WHATDO~EXI’?
Students do research to determine how people who eat little or no meat can
have healthy diets. This research requires them to 1) survey vegetarians; 2)
do library research; 3) ask experts. We want them to construct the idea that
all the amino acids one’s body needs can be eaten in a diet that blends legumes
with grains. They then look at the staple diets of other cultures, building an
appreciation for the healthy and diverse diets that have been created by
cultures that have little or no access to meat on a regular basis.
Food, Energy and Growth
TEACHER’S GUIDE
lab prep 15
MATERIALS AND ADVANCE PREPARATION
Chart of nutrients in various foods (in appendix.)
You may want to arrange to have students use the library during your class
period. They will probably need no more than 2 days for this assignment. For
those who are “asking an expert,” you might want to contact the local county
extension agency or university and set this up ahead of time with a nutritionist,
or arrange for a nutritionist to visit and talk to your class.
lab prep16
Michigan Department of Education
DO WE GET WHAT WE
P-@
NEED FROM W H A T W E E A T ? c, 4 *
Often when people think about getting what they need from what they eat, they
immediately start wondering if they have enoughvitamins and minerals in their
diets. They often don’t think about proteins, fats or carbohydrates.
Vitamins and minerals are important, although when people eat good food on a
regular basis they get the vitamins and minerals they need. Actually, proteins
and carbohydrates really make up most of the food you eat.
If you didn’t get enough protein in your daily diet, what wouldn’t happen?
If you didn’t get enough carbohydrates in your diet, what wouldn’t happen?
In this cluster, you will analyze your diet, and diets of other people around the
world, to see if you and they get enough of what you need to grow, to move, and
to think.
Food, Energy and Growth
Food, Energy, and Growth
57
TEACHER’S GUIDE
Lesson 14
/
c
DIET AND NUTRITION:
What do you eat?
You know how important it is for your body to get enough proteins and
carbohydrates from your food.
But how can you tell what’s in the foods you eat?
How do you know how much proteine, carbohydrates, and fats are appropriate
for you?
Teachers should encourage student
speculation here, but should not provide
answers at this; point.
Key
P
Question
How can you be sure that you get what you
need from your food every day?
You will try to figure out whether or not your diet is healthy for you, whether it
gives you what you need to grow and repair your body, and has the energy you
need.
First, you need to have a complete list of what you eat-a diet diary.
A. List everything you ate yesterday, from memory, on one sheet of paper. Then,
on another sheet, list today’s breakfast and/or lunch, any snacks, everything
you ate today. Take the list with you and keep recording all your food until
you go to bed. Bring it in tomorrow. Don’t cheat. Only you will aee this list,
so make it complete.
B. Then, you’ll need some way of figuring out how much protein, carbohydrate,
and fat you get from your food. How could you figure this out?
One way is to do food tests on everything you eat, like we did earlier in this unit.
Were those tests able to tell you how much protein, for instance, was in a piece
of cheese? Not really, not the way we did them. They could tell you ifprotein was
in cheese, but not how much.
But it seems possible to construct a teat like those to tell how much protein, or
carbohydrate, or fat is in a certain amount of food. In fact, food and nutrition
scientists have done this, and their results are on many packages of food you eat!
Here’s what a food analysis of bran flakes cereal looks like, taken right off the aide
of the box:
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Lesson Statement: Students compare foods based on nutrition information on food
Lesson
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TG 58
labels. They consider “common sense” guidelines for eating well and compare these to
the “Eating Right Pyramid,” Then they examine their own diets and two make-believe
diets,
Purpose: To enabIe students to use food labeling and other tools for constructing healthy
diets.
Approximate Time: 4 class periods
Michigan Department of Education
1 oz.
bran flakes
90
3g
carbohydrate 23 g
fat
og
cholesterol
Omg
calories
Protein
with l / 2 cup
skim milk
130
7g
29 g
og
Omg
with l/2 cup
whole milk
160
7g
29 g
4g
15 mg
For comparison, here’s what a food analysis of "crunchy” peanut butter looks like:
2 tbs.
peanut butter
calories
130
protein
9g
carbohydrate 5 g
C. Compare bran flakes with skim milk to peanut butter. In yourjournal, enter
the nutritional information for "bran flakes with milk in one column and
"peanut butter” in another, right next to it, to make it easier to compare.
1. Which would give you more protein?
1. peanut butter
2. Which would give you more fat?
2. peanut butter
3. Which would give you more carbohydrates?
3. bran flakes with milk
D. Try serving yourself 1 oz. of bran flakes with 1/2 cup of milk, and 2
tablespoons of peanut butter (maybe on a slice of bread) to see if these
nutritional analyses are really for what you would consider to be 1 serving.
4. Is 1 oz. of bran flakes with 1/2 cup of milk exactly what you would eat for
breakfast? Is 2 tablespoons of peanut butter exactly how much you’d eat
on a sandwich?
5. Are these comparisons true no matter how much you eat of either of these
foods?
E. Now do this kind of comparison with other foods you eat. Create a chart to
carry home with you, along with your record of what you eat, to collect
nutrition information from the sides of food packages. Try to find information
on many different foods, both ones that you think are healthy and ones that
seem like junk foods. ‘I’ry to get some that are high in protein, some that are
Food, Energy, and Growth
4. Probably no for bran flakcs. Probably
yes for peanut butter.
5. No. The assumption underlying the
comparisons of nutritional information
on package labeling is tbat the amount
indicated represents 1 serving. Often it
doesn’t.
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high in fat, some that are high in carbohydrates. Try to find information on
the foods that you tested in Cluster 1.
6. Meat, eggs, bulk foods, soda pop,
any foods that are already prepared, like
from a deli, or food delivered to your
home, like pizza. Also highly prepared
foods, like cakes and pies. You might
find out by calling a nutritionist at a
university, a hospital, or the county
extension 4-H office.
6. What kind of foods do you think don’t come with nutritional labeling7
How could you find out what a nutritional analysis of those foods would be?
Tomorrow you11 look at the nutrition information you’ve gathered. But before
you can really use this to help you know what kindof diet is good for you, you need
to think about a few common sense rules.
What common sense rules do you know about eating healthy? Brainstorm them
and list them on the board or on a piece of paper.
***
Here are a few:
l
l
l
7. Common senseruleshelpusmaintain
healthy bodies, even though we don’t
of red meat, or lots of cheese, or lots
7. Why do we have these common sense rules? Explain why you think each
one is important.
fully understand why certain foods are
good or bad for us. Sweets contain
sugar, which gives you energy, but also
causes cavities. Actually, the energy in
sugar is released much faster than the
energy in non-sugar carbohydrate foods
(like cereals and pastas). so that nonsugar carbohydrate foods are actually
better for continuing to get energy
between meals. Fats in foods, especially
saturated fats,, tend to clog arteries and
lead to heart disease. Fruits and
vegetables contain lots of good vitamins
and minerals.
8. Rules might include eating lots of
carbohydrates for energy; eating protein
foods when you’re growing.
9. a) Answers vary, but foods high in
fats or concentrated sugars should be
avoided.
b) Answers vary but a healthy diet
consists of plenty of grains, fruits and
vegetables. (See #7.)
Don’t eat too many sweets.
Don’t eat too many fatty foods, like lots
of peanut butter.
Eat lots of fruits and vegetables.
8. List any other rules you know about eating healthy. Try to make some up
from what you’ve learned so far in this unit.
Day 2
Now that you’ve collected all this nutritional information about different foods,
see if you can eort it out in some way.
F. Create several class charts for listing different types of foods -- one for foods
that are relatively high in proteins, one for foods high in carbohydrates, and
one for foods high in fats.
9.
a) Look at your chart, and think about your eating rules. What foods
should you stay away from, and why?
b) What foods should you eat, and why?
10. Are you surprised by any of these foods, that they have more protein,
or more fats, or more carbohydrates than you thought (or less of any
of these)?
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Michigan Department of Education
10. Answers vary.
Nutrition information for common foods is listed in the appendix, in case you want to
use some foods for comparison that no student brings back to class.
Lesson
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Here’s a rule-of-thumb for the amount of fat in a healthy diet: Nutritionists
recommend that no more than 30% of one’s daily intake of calories come from fats. This can
be estimated easily from the amount of grams of fat one eats: Each gram of fat has 9 calories
(compared to about 4 calories each for a gram of protein or a gram of carbohydrate): multiply
the number of grams of fat in the serving by 9 to get the total calories from fat, then divide
this by the total calories for the serving. Try this using the nutrition info on a candy bar.
Michigan Department of Education
Food Guide Pyramid
A Guide to Daily Food Choices
The U. S. Department of
Agriculture has created a simple
way to think about how much of
different foods people should eat.
It’s called the Eating Right
Pyramid. Let’s see if you agree
with their suggestions.
1
11. a) Which group(s) on the food pyramid are composed mostly ofprotein?
b) Grains (Bread, cereal, rice and
b) Which group(s) are composed mostly of carbohydrates?
pasta)
c) Meat and dairy products. If
students have trouble with this one, point
c) Which group(s) contain the most fat and oil?
12. Look at the shape of the pyramid and the recommended number of
servings for each group of foods and tell why breads, g-rains and cereals
are at the bottom of the pyramid and fats, oils and sweets are at the top
of the pyramid.
13. Do your ideas about eating well fit with this food pyramid? Why or
why not?
4 Try This
Let’s test out what you know about eating well by looking at three different diets
and analyzing them for proteins, carbohydrates, and fats.
You will n e e d :
for on4 day
Blank charts for recording data
* Marta's diets before and
the food unit
l
Your own diet diary
l
Here’s what to do:
Basically, you will look at three different teen-age diets: Marta’s (a fictitious
character) before studying the unit, Marta’s diet after studyingtheunit, and your
own sample diet for a day. You will analyze each diet, using nutritional
Food, Energy, and Growth
11. a) Meat products
out the key on the “Eating Right
Pyramid” which shows fats by the small
circles.
12. The bottom of the pyramid, which
has the most space represents foods that
you should consume in the largest
amounts. Breads. grains and cereals are
needed by bodies because they are good
sources of long-lasting carbohydrates
for energy. The top of the pyramid
which has the smallest space represents
food that you should consume in the
smallest quantities. Fats and sweets are
herebecausetheycancontributetohealth
problems, including heart disease and
cavities.
13. Answers vary.
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You may need to help students figure
out what the components of some
preparedfoodsmaybe. Theyoftenhave
trouble with this since their familiarity
with food is primarily from the
supermarket rather than from any actual
food production processes. Even foods
as common as cereal leave some students
totally mystified about where it comes
from.
information from food labels and the food pyramid, to see which components are
present and at what levels.
A. Examine Marta’s diet diary for the day before she studied this food unit.
Obtain a blank copy of the food pyramid and for each food consumed at
breakfast, lunch, dinner and for snacks, find the proper food group on the
pyramid and write the name of the food in that space. Items such as butter
or margarine, jam, syrup, topping, nuts, etc. should be entered aeparately.
MARTA’S SAMPLE DlETs
Students will need to estimate servings
in all of these questions. They should
have less difficulty with their own diet if
they kept an accurate food diary and if
they kept the packaging information
whenever possible. The wrappers from
snack foods and any others that they can
get will be very helpful in estimating
serving size as well as obtaining grams
of saturated or unsaturated fat and
cholesterol. You will probably need to
remind them that they should make the
best estimate they can.
BEFORE FOOD UNIT:
AFTER FOOD UNIT:
Breakkfast:
5 pancakes with butter and syrup,
4 strip of bacon. whole milk
Breakfast:
2 poached eggs, 2 slice of toast with honey.
skim milk, orange
A.M. Snack:
Sweet roll and soft drink
A.M. Snack:
Cottage cheese and pear
Lunch:
Hamburger, french fries. ice cream, soft drink
Lunch:
Broiled chicken, baked potato, apple, skim milk
P.M. Snack:
Candy bar and soft drink
P.M. Snack:
Raisins. apple juice
Dinner:
Steak, mashed potatoes with butler. peas.
fruit cocktail. apple pie, whole milk
Dinner:
Steak, baked potato with SOW cream, peas,
salad with b-cai dressing. cantabupe, cottage
cheese, skim milk
Bedtime Snack:
Potato chips and soft drink
Bedtime Snack:
Yogurt and apple
B. Count the number of servings of gmin products in Marta’s diet. Use the
information on the chart next to the "Eating Right Pyramid” as a guide in
counting servings. If packaging from any of these foods are available, the
nutrition information on it may help you, especially when evaluating your
own diet.
C. In a similar manner, count the number of servings in the fruit and vegetable
group.
D. Count the number of servings in the dairy group and in the meat products
group.
E. Use the information in the “Eating Right Pyramid” to estimate how many
grams of fat are in the diet. You will need to check through all the groups in
the pyramid, but especially the dairy and meat products groups for fat and
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Lesson
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Michigan Department of Education
oil content since most fats and oils are consumed as part of other foods.. For
example, potato chips are a vegetable but have large amounts of oil as do all
fried foods. Many meats and dairy products have high fat content as does
chocolate and most candies.
F. Use the information in the “Eating Right Pyramid” to decide how many
servings of concentrated sugars are in the diet. Again, you will need to check
through all the groups in the pyramid but especially the carbohydrate and
fruit groups. For example, pie is often a source of fruit but also contain
concentrated sugars. Cookies and cakes have wheat or oats (grain) in the
flour but also contain lots of concentrated sugars.
G. Now compare "Marta’s Food Pyramid before food unit” with the “Eating Right
Pyramid.” Be sure to examine and compare every food group. Remember that
the pyramid is a guide of what to eat each day and how many serving.
13.a) Not very
13. a) How healthy is her diet?
b) What suggestions can you make that will improve it?
H. Now look at Marta’s diet diary for the day after she had completed the study
ofthisunit. Beginwith anewblankcopyofthefoodpyramidandrepeatstepe
A through G.
b) Much less fat, meat, whole milk
products, concentrated sweets and junk
food
I. Compare “Marta’s Food Pyramid after food unit” with the “Eating Right
Pyramid.” Be sure to examine and compare every food group.
14. a) Quite healthy
14. a) How healthy is her diet?
b) Make suggestions if you can that will improve it.
b) Could eat less meat and more
grain
&%*a@
It’s one thing to criticize others for their eating habits. It’s harder to look closely
at what we eat ourselves.
J. Do the same kind of analysis on your own diet as you did on Marta’s diets.
15. a) How healthy is your diet?
15. Answers will vary.
b) What changes could you make in your own diet that would make it
healthier?
c) What might keep you from changing the way you eat?
16. a) Which diet was the healthiest? Give reasons to support your
answers.
16. Answers will vary.
b) Which one was most unhealthy? Give reasons to support your
answers.
Food, Energy, and Growth
63
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Food, Energy, and Growth
TEACHER’S GUIDE
l’G 63
DIET AND NUTRITION:
How do others eat?
Lesson 15
Most people in the United States eat fairly large portions of meat every day. It
may be in a sandwich for lunch, or as part of dinner. Meat is almost always the
main part of meals eaten in restaurants-think of what you eat in fast-food
restaurants, or how menus are often organized by “beef, chicken & fish.”
Meat is generally an excellent source of protein (although you wouldn’t want to
eat too much meat with high fat-content.) Meat is considered a “complete” source
of protein because all of the amino acids your body needs to make new cells are
available in meat.
This isn’t true of other foods that contain proteins. Grains (like wheat and oats),
legumes (like kidney beans, black beans, and peanuts) and many vegetablea
contain some proteins, but there are fewer types of amino acids in their proteins.
None of them alone contains all of the amino acids your body needs.
A. Look at your list of components of various foods. Write a list in your journal
that ranks the tap tan foods by the amount of protein they contain.
1. Meats contain more protein than
almost any other food.
1. What does this list tell you about the amount of protein in meat
compared with other foods?
2. No
2. Can you tell from this list which amino acids are available from each
protein-rich food?
***
It’s a good thing that meat isn’t the only source of protein. Many people in the
US., for various reasons, prefer not to eat meat-including chicken and fish. But
vegetarians are healthy-they grow well and repair their cells as needed, just as
do people who eat meat.
Ten of the 20 amino acids can he made
by the body, but 10 cannot; nor can they
be stored in the body. The ten that cannot
be made are called “essential” and need
to be eaten every day.
So what do vegetarians eat that gives them all of the amino acids they need for
growing and building strong hody parts? In other words, how can a person
construct a healthy diet that supplies all of the essential amino acids (and
vitamins and minerals) without eating meat?
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Lesson
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Michigan Department of Education
This is a good question. It’s good because, first of all, it’s important. But,
secondly, there are probably several different ways oflooking at the answers, and
several different ways of finding answers.
How could you find an answer to this question?
How could you and your classmates together, acting as a research team, come up
with good answers to this question?
***
Here’s how you might begin: Assign small teams of investigators to try several
different approaches to finding this out. One team could seek out and survey
several people who follow vegetarian diets, and ask what they do. Another team
could try working with a librarian to find library resources that might help. A
third team might try calling experts, like a nutritionist at a university or county
extension agency.
l
Do a survey
l
Use library resources
l
Talk to experts
After each small team of investigators ha8 compiled information from their own
inquiries, then your entire class should come together to pool the information
you’ve gathered and try to synthesize an answer to the question that makee
sense to every team.
B. After conducting small group research, hold a c l a s s discussion where
each group reports on their research and writes key ideae on the board. At
the end of all presentations, have several people try to summarize all three
reports and construct a good explanation of how vegetarians construct diets
that provide all their protein needs.
Food, Energy, and Growth
65
Here’s what students will probably find
out: While meat is a “complete” source
of protein, certain other foods can be
combined to provide all of the amino
acids that our body needs. Corn (for
example) is short on the amino acid
lysine, but rich in methionine. Soybeans
are rich in lysine, but short on methionine
(as is milk.) So if a person eats both corn
and soybeans at the same meal, all of the
essential amino acids are present in her
digestive system, for making new human
tissue protein. (An analogy to this might
be if one wanted to place the names of
new movies on a marquee, but they were
missing the letter “D” in their bucket of
letters. Theywouldneedtogetadifferent
bucket of letters that contained D’s.)
In general, grains and legumes can be
combined to provide the essential amino
acids. This has become a rule of thumb
for vegetarians: to eat both grain and
legumes at meals.
But vegetable sources of protein do not
providethesamequantityofproteinas
meat sources, so more food mass has to
be consumed.
Historically, the indiginous people of
Central and South America harvested
two vegetable crops that were very high
in both quantity and quality of protein
(that is, they were protein-rich and
contained most of the essential amino
acids.) They were spirulina, a bluegreenalgaescrapedoffthetopsoflakes,
which contained all of the essential
amino acids, and amaranth, a grain crop
equally as important as maize and beans.
Vitamins and minerals in our diets: Primary sources of vitamins and minerals include
vegetables and fruits. Some students may be interested in why we need so many different
vitamins and minerals-what each does for us, or what would happen if we had a deficiency of
any one of them. You might ask them to do some library research on this; we have listed a
description of the function of different vitamins and minerals in the appendix.
Lesson
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Food, Energy, and Growth
TEACHER’S GUIDE
TG65
Here’s another way of asking the same question about protein and meat, only
about different people.
We know that people in other cultures, including people in the United States
with different cultural heritages, eat different types of food. What’s your sense
of what people in other cultures eat?
3. Think for a minute about people in Mexico, for example. What picture do
you have in your head about how average people in Mexico eat? How
healthful would you think their diets are, in terms ofenougb carbohydrates
for energy and enough proteins for growth?
3. Students typically have misconceptions about the diets and quality of
life of people in other cultures.
Take a look at a typical diet for people living in different places around theworld:
Mexico - Corn Tortillas and dried beans
Southern United States - Rice and black-eyed peas
United States - Peanut butter and bread
China - Rice and bean curd
Japan - Fish
India - Rice and lentils
Italy - Spaghetti and cheese
Eskimo - Seal or whale meat
Tuareg Tribe of the Sahara - Millet and lentils
4. Healthy vegetarian diets must both
grains and legumes in order to obtain all
the amino acids needed for growth and
repair. In addition, everyone needs
plenty of fresh fruits and vegetables in
order to obtain the needed vitamins and
minerals.
You may want to pose the following
questions to students as they are
developing an understanding of how
other culture’s diets are nutritious:
4. Using your chart of the components of various foods, and your
understanding of how vegetarians get the different amino acids they
need, determine the “healthfulness” of the typical menu of several
different cultures.
1. Are the protein sources complete
or complementary?
5. Are you surprised by what you have discovered?
2. If the proteins are complementary,
what food is from the legume family and
what is from the: grain family?
3. What is wrong with a diet that
consists mainly of rice or cereal?
4. Why are baked or refried beans
sometimes served instead of meat?
5. Suggest three other combinations
of vegetables that would provide a
balanced diet.
***
Actually, the peoples who lived in the Western Hemisphere before Europeans
arrived made important contributions to the variety of healthful foods available
to the world. Corn, potatoes, peppers all originated here, and were carried back
to Europe. Native American cultures (north and south) sustained their people
on very healthful and diverse diets, although they did not include much meat,
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5. Answers vary.
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Michigan Department of Education
because of the difficulty or expense of obtaining it. Their healthful diets were
constructed from the foods that they cultivated in their own special climates.
Those diets form the basis of today’s meals throughout the Americas, including
familiesin the U. S. with cultural ties to Mexico, Central and South America, and
the Caribbean.
And what we have been discovering holds equally true for cultures that
originated in Africa, the Middle East, and Asia. All around the world people have
established for themselves healthful, sustaining, and diverse diete based on
what they can grow and catch. These diets were the results of agricultural
technology and experimentation in every culture.
These diets may be somewhat different from yours, or you may have ties to one
of these highly successful cultures in which many diverse, nutritious, and tasty
foods originated. Food is a part of everyone’s cultural heritage. Enjoy!
Food, Energy,
Growth
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All living things need food. Food supplies the energy needed for
life activities (moving, breathing, sensing, growing, reproducing),
and the materials needed for growth and repair.
Unit Content
Summary
Animals, including humans, have always relied on plant parts
for food (see the K-4 unit, “Running on Energy.“) Green plants
are unique in being able to manufacture new food, by capturing
energy from the sun and storing it in sugar molecules (glucose>
made from carbon dioxide and water. These sugar molecules are
built up into the various structures of plants (leaves, stems,
roots, seeds, fruits, flowers, and so on), eventually becoming all
of the different types of food that all living things use (see the 5
7 unit, “The Lives of Plants.“)
Animals, then, spend most of their lives undoing the work of
plants: Converting sugar molecules into carbon dioxide and
water, releasing the energy stored in sugar to use in the conduct
of their lives; and breaking apart the parts of plants in order to
build up again the parts they need for their own bodies. How
animals do this (especially how humans do this) is the subject of
this unit.
It starts with digestion.
Energy is a very difficult concept
forstudentstounderstand. They
know that it is needed to survive
but seldom can explain how it is
obtained. Even adults are
sometimes naive about energy
when they think that it comes
from exercising.
Digestion
And it starts in the mouth. Food (which in general is made up of
carbohydrates, fats, and proteins-see the product labeling on
any food package-as well as small amounts of vitamins and
minerals) is first physically broken into smaller pieces, and then
mixed with saliva, which contains an enzyme that chemically
changes some of the carbohydrates (mostly starches) into simple
sugars (including glucose.>
Food then moves down the esophagus into the stomach where
more enzymes mix with it as it is churned and turned. Some of
those enzymes convert more carbohydrates into glucose; others
begin to break down proteins into amino acids.
Finally, food moves into the small intestine, traveling through 30
feet of it (in adult humans) while the process of digestion is
completed. Continuing the digestion of carbohydrates and
proteins, new enzymes begin to react with fats, breaking them
down into fatty acids and glycerol. The new molecules produced
by digestion-simple sugars, fatty acids, and amino acids-are
water soluble.
Food, Energy and Growth
TEACHER’S GUIDE
Appendix 1
Circulatory system Then the circulatory system takes over.
Its function is to move these small, relatively simple molecules to
all of the cells of the body.
The digested materials leave the small intestine and enter the
circulatory system through tiny openings or holes in the walls of
the intestine and bloodvessels. Since these substances are water
soluble, they can be absorbed by the blood and can move with it
all over the body. (Undigested non-soluble food particles which
could not get out of the small intestine move into the large
intestine and finally out of the body as feces.)
While many studentsknow that
food is digested in our bodies,
they often believe that it “gives
up its energy” in the stomach.
Theyoftendon’tunderstandthat
it then moves out to all cells of
the body, where it releases its
chemical energy.
And constantly, all over the body, the digested substances leave
the blood stream and enter the cells. It is in the cells where all
the really important action takes place: releasing energy for life
activities; building new materials for growth and repair.
All three substances-simple sugars, fatty acids, and amino
acids-can be used to release energy, although it is primarily the
simple sugars (which come from carbohydrates) that are used
first. The fatty acids and amino acids (from fats and proteins) are
the building blocks of new materials-the new materials that
build longer bones, larger muscles, new skin, new blood as we
grow and as we repair damaged and worn out body parts.
Cellular How do cells release the energy of simple sugars? The cells of all
respiration living things do this, from humans to mice to worms to amoebas,
and not only animals, but all living things, including plants. Even
plants use their own glucose as food, to release the energy they
need for their life activities.
Cellular respiration can
generally be represented by the
followingequation, although the
actual process consists of a series
of more complex chemical
reactions:
C,H,,O,+ 60,--9 6H,O + 6C0, +
energy
Students seldom relate the need
for oxygen with energy
production.
Appendix 2
What goes on in cells is a series of complex chemical reactions
that use oxygen (this is why we breathe!) to break down glucose
into carbon dioxide and water, releasing the energy (originally
from the sun) stored in the glucose (by plants.) Carbon dioxide
and water are waste products that are removed from the cell and
carried away by the circulatory system to the lungs-where the
carbon dioxide and some water vapor are breathed out-and to
the kidneys-where water is discarded in the urine.
To illustrate this process of cellular respiration a bit more:
During vigorous physical activity, the need for glucose and
oxygen increases with the increased need for energy. When
you’re exercising vigorously, you know that you have to breathe
faster (to take in more oxygen), and-ifyou control how much you
eat-the extra glucose you need will be converted from the fat
Michigan Department of Education
your body normally stores from excess food.
Also during exercise, the production of water and carbon dioxide
increases. The increased heart and breathing rate is the body’s
way of delivering and removing these extra materials to and from
the cells during this increased activity.
Some of the energy released in cells is heat energy, which
maintains your body temperature or heats you up when you
exercise. But most of it (about 60%) remains as chemical energy,
transferred to many special molecules (called ATP) in the cell,
each of which can store the energy in very small usable quantities.
These energy-rich ATP molecules move around the cell, supplying
the energy needed by cells for life processes. The chemical energy
in ATP molecules can be changed to motion in muscle cells, to
light in the light-producing cells of the firefly, or to electrical
signals in brain cells. It is used to move blood, repair wounds,
move the lungs to breathe, and make new cells.
When students have heard of
respiration before, they usually
think of it simply as breathing.
Students easily associate the
need for energy with motion or
exercise but seldom associate it
with other cellular processes.
Now the next question is, what happens with food to help people Growth and repair
grow and repair damaged tissues? Again, this happens at the cell (protein synthesis)
level.
We grow by adding new cells to our bodies, new muscle cells, new
skin cells, new heart cells, new blood cells, new blood vessel cells,
etc. etc. Where do these new cells come from? They are made out Students don’t usually recognize
of the materials in food: the building blocks of fatty acids and that new body growth requires
amino acids.
new materials that have to come
Fatty acids are the building blocks for new fats and oils, which
primarily make up cell membranes. Amino acids (along with
nitrates and other minerals) are used for making specific new
proteins, different from the ones in the plant and animal materials
we eat. Some of these proteins are used for the inside components
of new cells-the structures that allow nerve cells, for example,
to pass electrical signals, or that allow muscle cells to contract.
Some are exported out of certain cells to play important roles in
fighting off disease (antibodies), or to regulate the action of
organs (hormones) by acting as messengers or message receptors
between cells. Some are used for the material that makes up
hair, nails and teeth. Also, perhaps most importantly, protein is
used to make enzymes. Enzymes are all over the body, not just
in the digestive tract. They are needed to make many chemical
reactions occur in cells.
from somewhere. In other words,
they don’t apply any knowledge
they may have of conservation
ofmatterin thiscontext of eating
and growing.
The process of building new molecules is a critical function of
cells. It uses the building blocks supplied by food, it requires
Food, Energy and Growth
TEACHER’S GUIDE
Appendix 3
In spite of their importance in
living systems, most students
have never heard of enzymes
except perhaps in the digestive
system.
Diet and nutrition
energy from cellular respiration, and it is directed by instructions
coded in the DNA. Our bodies are alive with internal activity,
even when we sleep!
So in order to grow and maintain a healthy body, humans must
eat sufficient quantities of carbohydrates, proteins and fats
(along with vitamins and minerals) to supply all of the materials
needed for growth and repair as well as all of the body’s energy
needs. This is why parents have always been concerned about
their children’s diets, and why world health organizations are
concerned about food supplies in developing countries.
Nutritionists tell us that we don’t need as much protein as we
once thought, but the types of protein we eat are important; that
we need complex carbohydrates for long-lasting energy supplies;
and that we need very little fat in our diets.
In general, American diets include too many calories and too
much fat (especially saturated fat), cholesterol, and salt, and too
few complex carbohydrates and fiber. These diets are generally
believed to be one reason for the large numbers of cases ofobesity,
heart disease, stroke and cancer in Americans. However, the
exact role of the diet in preventing some of these diseases is not
well understood.
While many Americans are replacing the traditional diet
represented by hamburgers, french fries, and shakes, many
diverse cultures both within the U.S. and around the world have
traditionally had much more healthy diets.
There are almost as many ways of meeting nutritional needs as
there are cultures in the world. In most places, the food people
eat is that which comes from their natural environment, rather
than that which they import. This includes harvests from the
land and the surrounding sea. Cultures all over the world,
including those of which many students in the United States are
decendents, have developed ingeneous ways of meeting their
nutritional needs, including the need for sufficient carbohydrates
for energy and sufficient and complementary proteins for the
numerous amino acids needed for protein synthesis.
Appendix 4
Michigan Department of Education
Class
Name
Food, Energy and Growth
lNSTRUCTIONs: Please answer these questions to the best of your ability, without
asking anyone for help.Theresultsofthistestwill~beusedforyourgrade.
Please be as complete in your answers as you can. The more you write the more
we will know for revising this unit. Even ifyou think that you haven't covered
what’s in an item, please write the best answer you can
0 1992 Michigan Dept of Education; developed by Edward Smith, Theron Blakeslee, &
Joseph Vellanti
1. At the right below is the nutrition information from the label of a jar of peanut
butter. Use the information in this chart to answer the following questions:
a) What nutrient(s) (food components) do you think this peanut butter is high in?
Nutrition Information
Per Serving:
Calories . . . . . . . . . . . . . . . . . . . . 170
Protein . . . . . . . . . . . . . . . . . . 9 grams
Carbohydrate . . . . . . . . . 4 grams
Fat. . . . . . . . . . . . . . . . . . . . . .15 grams
b) Explain why you would not want to eat peanut butter sandwiches every day.
2. Your body needs energy for all of its activities. Where can it get this energy?
a. from resting
b. from food
c. from exercise
d. from vitamins
(Circle as many choices as you want.)
1
3. Most teenagers are physically active and still growing. Identify three foods
that could be part of healthy diet for a teenager. For each food, explain why that
food would contribute to a healthy diet by identifying a food component (nutrient)
that it provides and explaining why each food component is important in a
teenager’s diet.
Food Item
.
.
provided,
.
vthem
a.
b.
C.
4. Which of the following are products your body can use that are likely to result
from the digestion of food. Circle your choices. You may circle more than one.
fats
sugars
starches
proteins
complex carbohydrates
simple sugars
amino acids
carbon dioxide
fatty acids
vitamins
oxygen
5. When you eat a turkey and cheese sandwich for lunch, parts of the sandwich
get digested over the next few hours.
a) What happens to the sandwich as it gets digested?
b) Why does the sandwich need to be digested?
this question continued on next page
2
c) What materials result from the sandwich being digested?
d) Where in your body are these digested food materials used?
e) What happens to these digested food materials after they get to where they are
needed?
6. After running for a few minutes, a person will breathe more rapidly than
before.
What benefit to your body is there in breathing faster when you are running?
Explain as completely as you can. Make sure you talk about what your body does
with the additional amount of oxygen the runner takes in.
7. Since the time you were five years old, you have probably grown quite a bit. For
example, the muscles that move your fingers are longer and larger. Explain as
completely as you can how the muscles that move your fingers came to be so
much bigger, and what food has to do with this growing.
3
8. You have probably had a cut somewhere on your hands or feet. When the cut
healed, it may have left a scar or there may be no sign left of the cut at all.
a) Where does the new shin come from that covers over the cut?
b) What is going on in the shin cells around the cut as the cut heals?
c) What hinds of food components help your body to heal cuts in your shin?
U
9. When you inhale your lungs take in oxygen from the air. The oxygen is then
carried by your blood for use in your body.
a) Where in your body is the oxygen needed/used?
b) How is the oxygen used after it gets to where it is needed?
4
10. The air you breathe out contains more carbon dioxide (CO,) than the air you
inhale.
a) Where in your body does the new carbon dioxide come from?
b) Where does the carbon in the new carbon dioxide come from?
11. Which of the following are needed by the cells in the muscles in your arm?
energy
Not needed_
needed_
Why needed?
oxygen
Not needed_ needed_
Why needed?
carbon dioxide Not needed_
needed_
Why needed?
12. A healthy diet should contain at least 2 servings of meats, poultry, fish, dry
beans, eggs or nuts each day.
Suppose you were trying to convince a younger brother or sister to eat more of
these foods. How would you explain to them the importance of these foods in their
diet?
b) If you said, as your answer to 12a, that you need to eat these foods to be big and
strong, then explain how food helps you to be big and strong.
5
13. If someone eats a lot of food, he or she will gain weight, perhaps in the form
of fat around the waist. How is it that sometimes eating food will add fat around
your waist? (Write about fat cells if you can).
14. If you are standing on a scale to weigh yourself, and you take a brick out of
your pocket and drop it on the ground, you would lose weight, right? When you
exercise, you can also lose weight. What is it that leaves your body to make you
lose weight when you exercise?
b) Explain why exercise helps you lose weight.
6
U
The Food Guide Pyramid
A Guide to Daily Food Choices
Fats, Oils & Sweets /
USE SPARINGLY
Milk, Yogurt &
Cheese Group
2-3 SERVINGS
Bread, Cereal,
Rice & Pasta
/ Group
.
Sweets Group
RecommendedAmounts:
Concentrated sweets should be consumed sparingly
preferably, no more than once a day. This is because
thesesim@esugarsareusedupvefyqulcldybythe
body while the complex carbohydrates from the grain
group can be used for energy for several hours.
count as one serving:
1 piece of ple or cake
1 large cookie or 2 smaller cookies
1 piece of Chocolate candy
1/4 of a candy bar
Topplngs or jam. Jelly syrup. honey.etc.
Non-diet softdrinks
Honey or sugar-coated cereals
Milk, Yogurt and Cheese Group
Court as one serving:
1 cup milk or milk products such as yogurt, cottage
cheese, Ice cream, etc.
1/2 ounces cheese
Fats and Oils
Recommended Amount:
30% or less of your total calories should come from
fat with less than 10% from saturated fat which are
mainly from animal products.. Thls means about 33
grams of fat for each 1000 calories consumed. Most
15 to l8 year old females require about 2300 calories/
day and most 15-18 year old males require about 3000
calories/day. Those who are physically very active
will requlree more.
Count grams as follows
1 tablespoon of butter, margarine, salad dresslng,
mayonnaise=10 grams fat
1 small serving (3 oz.) beef or pork=12 grams fat
1 small serving (3 oz.) lean beef or poultry (without
skin)=6 grams fat
1 egg yolk=5 grams fat
1 cup whole milk or whole milk product=8 grams fat
l cup 2% milk or milk products=5 grams fat
1 cup 1% milk or milk products=3 grams fat
1 cup 1/2% milk or milk products=1 gram fat
Vegetable Group
Court as one servIng:
1 cup raw, leafy greens
1/2 cup of other vegetables
Breads, Cereal, Rice, l nrf Pasta Group
Court as one serving:
1 slice bread
1/2 bun. bagel or English muffln
1 ounce of dry. ready-made cereal
lxrwd
1/2 cup cooked cereal, dry pasta
Fruit Group
Count as one serving
1 medium apple, orange or banana
1/2 cup of small of diced fruit
3/4 cup fruit juice
Fats, Oils and Sweets
Milk, Yogurt &
Bread, Cereal,
Rice & Pasta
Group
Meat, Poultry, Fish
Dry Beans, Eggs &
Ii--
FOOD
COMPOSITION TA B L E
II
PROTE
SERVING
SIZE
(OUNCES)
CAL (9)
APPLE, RAW, W/SKIN. 1 AVG
5.3
69
0.3
APRICOTS. DRIED
3.5
237
3.6
FOOD
IN(g)
APRICOTS, RAW
AVOCADO, RAW,
BANANA
3.5
BLUEBERRIES, RAW
I 56
I 0.7
CANTALOUPE, RAW
GRAPEFRUIT, RAW, 112
z--k-k-
GRAPES W/SKIN. @36
ORANGE, RAW, PEELED
PEACH, RAW
PEAR, RAW W/SKIN
7.1
I
116
11.1
I 0.1
I 0
17.5
I 0.1
I 0
I 0.6
PINEAPPLE, RAW, 1 SLICE
STRAWBERRIES, RAW
R A W1 SLICE
,
ASPARAGUS, RAW, BOILED
2+-k--k
BUTTERNUT SQUASH, BAKED
fkk4-F
CABBAGE, RAW
CARROTS, RAW
CAULIFLOWER. RAW
CELERY, RAW
CORN-ON-THE-COB, BOILED
y-y-y
GREEN BEANS, BOILED
GREEN PEPPER, RAW
5.4
1.4
I 9
I 0.5
9.0
I 217
I
I 0.2
I 0
0.3
0
HUBBARD SQUASH, BAKED
LETTUCE, RAW
U
MUSHROOMS, RAW
POTATO, BAKED W/SKIN
6.0
46.9
FOOD COMPOSITION TABLE
CODFISH RAW
BROILED
SOURCES OF VITAMINS
Vitamin A
Egg yolks, butter, dark green and deep yellow
vegetables, organ meats, fish liver oil.
Vitamin B1
Seafood, poultry, meats, whole or enriched grains, green
vegetables, milk, soy beans.
Vitamin B2
Milk, eggs, poultry, yeast, meats, soy beans, dark green
vegetables, mushrooms.
Niacin
Leafy vegetables, peanut butter, potatoes, whole or
enriched grain, fish, poultry, meats, tomatoes.
Vitamin B12 Green vegetables, liver, meat, fish, eggs, milk
Vitamin C
Citrus fruit, melon, strawberries, tomatoes,
leafy vegetables.
Vitamin D
Milk, liver, eggs, fish liver oils.
Vitamin E
Vegetable oils, butter, milk, leafy vegetables,
whole grain cereal.
Vitamin K
Green vegetables, tomatoes, soy bean oil,
liver, cabbage, potatoes, peas.
SOURCES OF MINERALS
Calcium
Milk and other dairy products, bean curd, dark
green vegetables.
Phosphorus Meats and dairy products, eggs.
Sodium
Meats, dairy products, salt.
Chlorine
Salt
Potassium
Orange juice, bananas, dried fruits, potatoes.
Magnesium
Nuts, grains, dark green vegetables, seafood,
chocolate.
Iodine
Iron
Seafood, iodized salt.
Meats especially liver, dark green vegetables,
dried fruits, whole grains
SOURCES OF PROTEINS, FATS AND CARBOHYDRATES
PROTEIN: The best sources of protein are from animal, parts. These are considered
complete proteins because they contain all of the essential parts (amino acids) your
body needs for building purposes. Examples of complete protein include meat, fish,
poultry, eggs and dairy products (milk, cheese, yogurt, etc).
Protein from plants usually contain protein in lesser amounts and it does not
contain all of the essential building blocks (amino acids) for your body. These are
called complementary proteins. Examples of plant protein are cereal grains (rice,
corn, wheat, etc.) and legumes (most members of the bean, pea and nut families).
FATS: Only a few foods such as margarine or butter contain only fat. Usually fats are
found together with other nutrients. The fats are found in foods that come from both
plants and animals. Animal sources that are high in fat content include red meat, pork,
and whole milk or dairy products. Plant sources that are high in fat content include
nuts, olives and seeds (sesame, sunflower, peanut, etc.) and the oils made from them
which are used in cooking.
Fish, poultry, eggs, skim milk dairy products, some starchy vegetables and fruits
(corn, beans, peas, apples, etc.) have much smaller quantities of fat.
STARCH: Foods that are high in starch content include grains (wheat, rice, corn, oats,
etc.) starchy or non-watery vegetables (potatoes, winter squash, beets, beans, peas,
etc.) and fruits (raisins, prunes, bananas, dates, figs, etc.)
Foods that provide lesser amounts of starch are the watery vegetables (summer
squash, lettuce, cabbage, cucumbers, etc.) and fruits (grapefruit, oranges, grapes,
plums, etc.)
SUGAR: Highest in sugar content are the concentrated sweets such as candy, honey,
syrup, molasses, jam, jelly, and most non-diet soft drinks.
Foods that contain lesser amounts of sugar are all fruits and vegetables.
Edward Carlson
Dewayne Anderson
MSTA
Western Michigan University
Professor of Physics
Michigan State University
Richard Chase
Boberta Jacobowitz
Research Scientist
Ford Motor Company
Janet Kahan
Science Teacher
Lansing Otto Middle School
Science Education Coordinator
Midland Public School8
Barbara Mick
Wendell Moyer
Patricia Maldonado
Peter Vunovich
Dawn Pickard
Hugo Pinti
MEA
Lansing Eastern High School
Professor of Science Education
Oakland University
Greg
Advisory Board
Sarah Lindsey
Elementary Science Specialist
Ann Arbor Public School8
Principal
Crawford AuSable (Grayling El.) School8
Michigan
Science Education
Resources Project
Principal/MASSP
Sturgis High School
Outreach Director
Battle Creek Area Math&i. Cntr
Science Education Coordinator
Flint Public School8
Zulauf
Science Education Coordinator
Muskegon Intermediate School Diet.
Adelle Alim
Detroit Publ. School8
Juanita Chambers
Rose Arbanas
Calhoun ISD
Cherie Cornick
Detroit Publ. School8
Wayne Co. M/S Alliance
Bern. Ortiz De Montell
Brenda Earhart
Mary Edmond
Evelyn Green
Carmen Harris
Mozell Lang
Diana Marinez
Fred Page
Yvonne Peek
Dawn Pickzrd
Wayne State University
Grand Rapids Public School8
Michigan State University
Michigan State University
Project Staff
Joan Webkamigad
Michigan Dept. of Education
Kalamazoo Area Math/Sci. Ctr.
Lansing Comm. College
Michigan Dept. of Education
Detroit Public School8
Oakland University
Culturally-Relevant
Advisory Committee
State Board of Education, August, 1992
Dorothy Beardmore, President . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rochester
Dr. Gumecindo Salas, Vice President . . . . . . ..__.__.......... East Lansing
Michigan Science Education Resources Project
Staff Writers
Marilyn F. Lundy, Treasurer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detroit
Cherry H. Jacobus, NASBE Delegate . . . . . . . . . ...____........ Grand Rapids
Theron Blakeslee
Project Director
Leona Bronstein
East Lansing High School
Deborah Nesbitt
Roseville Junior High School
Yvonne Peek
Detroit Public Schools
Elma Tuomisalo
Ishpeming
Joe Vellanti
Lansing Eastern High School
Katherine J. DeGrow
w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eaton Rapids
Dick DeVos
s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grand Rapids
Barbara Roberts Mason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lansing
Annetta Miller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Huntington Woods
Ex Officio Members
John Engler
Governor
Funded through a grant from the W. K. Kellogg Foundation
Robert E. Schiller
Superintendent of Public Instruction
I-
Consultants
Howard Stein
Grand Valley St. University
Charles Anderson
Michigan State University
Edward Smith
Michigan State University
Pilot Teachers
John Bjorkquist & Jeff Riffle
Okemos High School
Chris Johnson & Dave Kirschinger David McCloy
Unionville-Sebewaing Mid. Sch.
East Lansing High School
Ted Falkenberg
Diane Thiel
Lincoln H.S. (Warren-Van Dyke P.S.) Port Hope Comm. Schools
Advisory Board
(See Inside Back Cover)
Special thanks to
Project assistant: Linda Vermeersch.
Artwork: Ida Castillo and Tony Johnson. Cover artwork: Steve Light.
Page layout: Tony Johnson. Editor: Sally Pratt. Thanks to the many
workshop participants who offered constructive suggestions for revising
this unit. Some of the material contained in this unit is derived from “The
Power Cell Teacher’s Guide, ” a teaching unit authored by Charles W.
Anderson, Kathleen J. Roth, Robert Hollon and Theron Blakeslec, and
published by the Institute for Research on Teaching, Michigan State
University, October, 1985.
How to use the “Food, Energy and Growth” unit:
(8th, 9th or 10th grade)
l
The student book: Each student should have a copy of the student book.
This book includes reading, lab activities, and discussion questions, all
integrated into lessons. The lessons are clustered into four sections
(simply called “Clusters”), each based on a key question.
l
l
l
background information to help teachers see the broad directions
and intent of the unit;
lesson background and lab preparation (on blue sheets prior to
each cluster) to prepare for the hands-on activities in each lesson;
lesson statement, purpose, and approx. time for each lesson;
margin notes on student thinking and content;
answers to questions posed in the text; and a
content summary (in the appendix) as background information on
the content.
Student journals: The student books have no space for writing answers
to questions, so that they can be used by several classes. For writing
answers, recording data from investigations, and posing new questions,
we recommend that students use a journal. Journals have several
advantages over single sheets of paper handed out and collected on a daily
basis: They let students compile their work, as in a portfolio, gaining
some sense of pride in their collection; and they allow students to look
back on their early ideas, appreciating the way their understanding grows.
Many different kinds of notebooks can be used as journals. In a few
lessons, prepared handouts are available for students’ use (in the appendix),
which can be kept in a pocket in their journal.
Overhead transparency masters: The appendix contains three drawings
of the human body, one showing the digestive system, one showing part
of the circulatory system, and one showing the lungs. These three can be
overlaid to illustrate discussions in the text.
Annotated teacher’s edition of the student book: The teacher’s guide
contains several pieces of information that should be helpful to teachers
as they prepare and teach this unit. They include:
Copyright 0 1992, by The State of Michigan. All Rights Reserved.
Local and Intermediate School Districts in Michigan are encouraged
to create copies for their own education purposes.
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Feel free to contact Mr. Theron Blakeslee, Project Director, at
(517) 373-0454 with any questions or concerns.