Download Round and Round Activity - Delaware Access Project

24
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ACTIVITY OVERVIEW
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40
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Round and Round
BO RA
T
SUMMARY
Students use their understanding of the circulatory system to model how the heart
pumps blood to the lungs and the rest of the body. They use pressure bulbs to model
the double-pump circulatory system of mammals.
KEY CONCEPTS AND PROCESS SKILLS
1.
Creating models is one way to understand and communicate scientific
information.
2.
Human body systems are composed of organs. The structure of an organ is
adapted to perform specific functions within one or more systems.
3.
Blood is pumped around the human body by the heart.
4.
Valves control the direction of flow and allow liquid to move under pressure
in both a pressure bulb and the human heart.
5.
The human heart is a double pump, which increases the efficiency of blood
circulation.
KEY VOCABULARY
arteries
model
blood vessels
structure
circulatory system
veins
function
Teacher’s Guide
B-159
Activity 24 • Round and Round
MATERIALS AND ADVANCE PREPARATION
For the teacher
*
1
overhead projector
*
1
1-liter beaker
1
180-mL bottle of phenolphthalein
1
60-mL bottle of 0.1 M sodium hydroxide
1
60-mL bottle of 0.1 M hydrochloric acid
1
dropper bottle of blue food coloring
For the class
pressure bulbs
45-cm (18-inch) lengths of clear plastic tubing
plastic bins (or buckets)
*
supply of water
*
red and blue colored pencils
siphon bulbs with tubing (optional)
overhead transparencies (optional)
transparency pens (optional)
*
sponges
*
mops
*
paper towels
*Not supplied in kit
n Teacher’s Note: Plan to introduce and test the models in one period. Student
presentations and the demonstration can be conducted during the next class
period. Practice the oxygenation model (that models oxygenation and deoxygenation of blood using phenolphthalein) ahead of time. If you are having
difficulty getting the color changes to work, use distilled water (you will need
about 2⁄3 gallon per class period).
To control potential spills, fill one plastic bin 3⁄4 full of water for each group of
four students in advance. Also have sponges, mops, and paper towels available to clean up any spills. Or you could conduct this activity outdoors.
B-160
Science and Life Issues
Round and Round • Activity 24
TEACHING SUMMARY
Getting Started
1.
Explain the Challenge question to the class.
Doing the Activity
2.
Student groups design a model.
3.
Groups work together to select and test a model.
4.
Groups explain to the class the model they constructed.
Follow-Up
5.
Discuss how the heart acts as a double pump.
6.
Demonstrate how a model can show changes in oxygen and carbon
dioxide levels of the blood.
Teacher’s Guide
B-161
Round and Round • Activity 24
TEACHING SUGGESTIONS
n
1.
GETTING STARTED
Explain the Challenge question to the class.
In this activity, students use pressure bulbs to
double-pump system, with each bulb representing
one side of the heart.
3.
Groups work together to select and test a
model.
model how the heart pumps blood to the lungs and
the rest of the body. Have students read the Chal-
Have each group share its design with another
lenge question (“How can you construct a model
group and come to agreement on which one design
to show how the heart pumps blood to the lungs
they should try. This provides an opportunity for
and the rest of the body?”). Explain that a good
students to defend their thinking as well as to gain
model will not look exactly like the circulatory sys-
experience in considering another group’s ideas. In
tem, but it will show how the heart pumps blood to
addition, working together makes more equipment
and from the same areas and in the same order as
available to construct the model.
in the circulatory system.
After groups have selected a model, they should
n
2.
DOING THE ACTIVIT Y
Student groups design a model.
This activity is structured as an open-ended assessment, with students working in groups of four. Each
group should come to agreement on a single design.
Have groups complete Step 3 of the Procedure (drawing and labeling their model) before working with
another group of students. You may wish to review
their designs before they go on to the next step.
work together to set up and test the model. If modifications are necessary, groups should work together to make them. Encourage students to record in
their science notebooks any changes they make to
their model.
4.
Groups explain to the class the model they
constructed.
After students have tested their model, they can
work together to prepare a short presentation that
explains their model to the class. You may wish to
While students may develop other models, several
provide student groups with overhead transparen-
possible models are shown on the next page. (In
cies and transparency pens for their presentations.
each diagram, rectangles represent plastic bins, ovals
They can use Analysis Question 1 as a guide.
represent pressure bulbs, and lines represent tubing.)
(Although the question is identified for a group of
Each model would transport water (blood) from one
four students, you may prefer groups to work
part of the body to the other. Depending on the
together for their presentation.) Encourage students
model that students develop, the aorta, pulmonary
to discuss their thinking and to describe any
artery, pulmonary vein, and sides (or chambers) of
changes they made to their model.
the heart could also be labeled. Note that Model 1,
which is the simplest, most accurately models the
Depending on the level of student understanding,
Teacher’s Guide
B-163
Activity 24 • Round and Round
Analysis Question 2 can be completed in groups or
times. This student simulates carbon dioxide enter-
individually. If completed individually, Question 2
ing the blood from body tissues.
can provide an opportunity for students to demonstrate their understanding of how a model relates to
the real structure. You can assess student work with
the Understanding Concepts (UC) variable.
n
5.
FOLLOW–UP
Have students begin pumping. The class should
notice a color change as the blue water moves into
the bin designated “lungs” (the water should begin
to turn pinkish-red). As red water re-enters the
“body” bin, it should turn back to blue. Ask, What
do the color changes represent? Red is used to
Discuss how the heart acts as a double
represent blood carrying more oxygen and less car-
pump.
bon dioxide, while blue represents blood carrying
Use Analysis Question 3 to discuss the various mod-
less oxygen and more carbon dioxide.
els presented in class. Ask, What were the
strengths and weaknesses of the various mod-
SUGGESTED ANSWERS
TO ANALYSIS QUESTIONS
els? In other words, how well did they model how
the heart pumps blood to the lungs and to the rest
of the body? An ideal model would represent the
heart as a double pump, simulating circulation to
1.
How well did your group’s original model
work? What changes did you make to
the lungs as well as to the rest of the body.
improve it? Discuss how your design showed how
6.
Demonstrate how a model can show
the heart pumps blood to the lungs and the rest of
changes in oxygen and carbon dioxide lev-
the body.
els of the blood.
Student responses will vary depending on the
Set up Model 1 (shown above) for the class demon-
type of model that they designed. Possible
stration. Fill each bin with 1,500 mL of water. In one
models are shown on the previous page.
bin (representing the lungs), place 10 mL of phe-
2.
a.
nolphthalein. In the other bin (representing the rest
Draw a diagram of your final model. Use
arrows to show which way the water flowed.
of the body), place 5 drops of blue food coloring and
10 mL of 0.1 M sodium hydroxide.
b.
Label the parts of your model that represented
various organs, structures, or systems of the
Designate one student to be “oxygen.” This student
should drop one drop of sodium hydroxide at a time
into the bin designated “lungs” only after the
“heart” has begun pumping. This student simulates
fresh oxygen moving into the blood.
Designate another student to be “carbon dioxide.”
This student should drop one drop of 0.1 M hydro-
human body.
c.
Use a red colored pencil to identify which tubing contained blood carrying more oxygen and
less carbon dioxide. Use a blue colored pencil to
identify which tubing contained blood carrying
less oxygen and more carbon dioxide.
UC
While student answers will vary based
chloric acid at a time into the bin designated “rest
on their model, be sure to check that all parts of
of the body” after the “heart” has pumped a few
the design are consistent within the model, i.e.,
B-164
Science and Life Issues
Round and Round • Activity 24
parts are labeled correctly, the direction of
3.
Compare the different models that were presented.
blood flow is correct, and the blood containing
Which design(s) modeled the function of the heart
more/less oxygen and carbon dioxide is colored
the best? Explain.
correctly. Possible level 3 answers are shown on
While various models are possible, not all of the
the next page of this Teacher’s Guide. Some stu-
models may have included a pressure bulb in
dents may identify a bin alone as representing
representing the heart. Designs that included
the heart. For example, consider Model 2 above.
the pressure bulbs in representing the heart are
Students may label the center bin as the heart,
better models of the functioning of the heart
leaving the bulbs outside the heart. Such a
than models that did not. For example, consid-
response would not merit a level 3 on the
er Model 2 above. Some students may label the
Understanding Concepts (UC) variable, since
center bin as the heart, leaving the bulbs outside
such an explanation would not accurately
the heart. In such a design, the pumping func-
model the role of the heart as a pump.
tion of the heart is not included in the model.
4.
Reflection: How does modeling help you understand how things work?
Students should respond that a good model
shows how something works in a way that is
visible and easy to understand.
Teacher’s Guide
B-165
Activity 24 • Round and Round
Model 1
more 02
more 02
less CO2
less CO2
less 02
more CO2
less 02
more CO2
Lung s
Rest of Body
Heart
Model 2
more 02
more 02
less CO2
less CO2
less 02
more CO2
less 02
more CO2
Rest of Body
Lungs
Heart
Model 3
e 02
mor
CO2
less
more 02
Liver
less CO2
less 02
more CO2
less
02
mor
e CO
Lungs
2
Rest of Body
Heart
B-166
Science and Life Issues