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CURRICULUM TOPIC STUDY GUIDE – SEASONS
I. IDENTIFY ADULT CONTENT KNOWLEDGE
Science For All Americans
The Earth (Pages 42 – 43)
We live on a fairly small planet, the third from the sun in the only system of planets definitely
known to exist (although similar systems are likely to be common in the universe). Like that of
all planets and stars, the earth's shape is approximately spherical, the result of mutual
gravitational attraction pulling its material toward a common center. Unlike the much larger
outer planets, which are mostly gas, the earth is mostly rock, with three-fourths of its surface
covered by a relatively thin layer of water and the entire planet enveloped by a thin blanket of
air. Bulges in the water layer are raised on both sides of the planet by the gravitational tugs of
the moon and sun, producing high tides about twice a day along ocean shores. Similar bulges are
produced in the blanket of air as well.
Of all the diverse planets and moons in our solar system, only the earth appears to be capable of
supporting life as we know it. The gravitational pull of the planet's mass is sufficient to hold
onto an atmosphere. This thin envelope of gases evolved as a result of changing physical
conditions on the earth's surface and the evolution of plant life, and it is an integral part of the
global ecosystem. Altering the concentration of its natural component gases of the atmosphere,
or adding new ones, can have serious consequences for the earth's life systems.
The distance of the earth from the sun ensures that energy reaches the planet at a rate sufficient
to sustain life, and yet not so fast that water would boil away or that molecules necessary to life
would not form. Water exists on the earth in liquid, solid, and gaseous forms—a rarity among
the planets (the others are either closer to the sun and too hot or farther from the sun and too
cold).
The motion of the earth and its position with regard to the sun and the moon have noticeable
effects. The earth's one-year revolution around the sun, because of the tilt of the earth's axis,
changes how directly sunlight falls on one part or another of the earth. This difference in heating
different parts of the earth's surface produces seasonal variations in climate. The rotation of the
planet on its axis every 24 hours produces the planet's night-and-day cycle—and (to observers on
earth) makes it seem as though the sun, planets, stars, and moon are orbiting the earth. The
combination of the earth's motion and the moon's own orbit around the earth, once in about 28
days, results in the phases of the moon (on the basis of the changing angle at which we see the
sunlit side of the moon).
II. CONSIDER INSTUCTIONAL IMPLICATIONS
Benchmarks for Science Literacy
The Earth – General Essay and Grade Level Essays (Pages 66 - 70)
An integrated picture of the earth has to develop over many years, with some concepts being
visited over and over again in new contexts and greater detail. Some aspects can be learned in
science, others in geography; some parts can be purely descriptive, others must draw on physical
principles. The benchmarks in this section complement those of the previous section that locate
the earth in the cosmos and those of the following section that focus on the surface of the earth.
This arrangement does not imply any particular order of teaching. Often, teaching near-at-hand
phenomena before teaching the far-distant ones makes sense; on the other hand, sometimes the
near-to-far progression that makes sense cognitively may not correspond to what interests
children.
Perhaps the most important reason for students to study the earth repeatedly is that they take
years to acquire the knowledge that they need to complete the picture. The full picture requires
the introduction of such concepts as temperature, the water cycle, gravitation, states of matter,
chemical concentration, and energy transfer. Understanding of these concepts grows slowly as
children mature and encounter them in different contexts.
The benchmarks here call for students to be able to explain two phenomena-the seasons and the
phases of the moon-that are usually not learned well. Most adults are unable to give even
approximately correct explanations for them. Most students are told by teachers what causes the
seasons and the phases of the moon, and they read about them without understanding. Moon
phases are difficult because of students' unfamiliarity with the geometry of light and "seeing." To
help figure out the geometry, students can act out the sun-earth-moon relationships and make
physical models. In trying to understand the seasons, students have difficulties regarding
geometry and solar radiation. Students need direct experience with light and surfaces-shadows,
reflection, and warming effects at different angles.
Kindergarten through Grade 2
There are many ways to acquaint children with earth-related phenomena that they will only come
to understand later as being cyclic. For instance, students can start to keep daily records of
temperature (hot, cold, pleasant) and precipitation (none, some, lots), and plot them by week,
month, and years. It is enough for students to spot the pattern of ups and downs, without getting
deeply into the nature of climate. They should become familiar with the freezing of water and
melting of ice (with no change in weight), the disappearance of wetness into the air, and the
appearance of water on cold surfaces. Evaporation and condensation will mean nothing different
from disappearance and appearance, perhaps for several years, until students begin to understand
that the evaporated water is still present in the form of invisibly small molecules.
Grades 3 through 5
During this period, students can begin to learn some of the surface features of the earth and also
the earth's relation to the sun, moon, and other planets. Films, computer simulations, a
planetarium, and telescopic observations will help, but it is essential that all students, sometimes
working together in small groups, make physical models and explain what the models show. At
the same time, students can begin learning about scale (counting, comparative distances,
volumes, times, etc.) in interesting, readily understood activities and readings. However, scale
factors larger than thousands, and even the idea of ratios, may be difficult before early
adolescence.
An important point to be made along the way is that one cannot determine how the solar system
is put together just by looking at it. Diagrams show what the system would look like if people
could see it from far away, a feat that cannot be accomplished. Telescopes and other instruments
do provide information, but a model is really needed to make sense out of the information. (The
realization that people are not able to see, from the outside, how the solar system is constructed
will help students understand the basis for the Copernican Revolution when the topic arises
later.)
In making diagrams to show, say, the relative sizes of the planets and the distances of the planets
from the sun, students may try to combine them using a single scale-and quickly become
frustrated. Perhaps this can lead to a discussion of the general limits of graphic methods
(including photographs) for showing reality. In any case, at this stage a rough picture of the
organization of the solar system is enough.
Grades 6 through 8
Students can now consolidate their prior knowledge of the earth (as a planet) by adding more
details (especially about climate), getting a firmer grasp of the geometry involved in explaining
the seasons and phases of the moon, improving their ability to handle scale, and shifting their
frame of reference away from the earth when needed. An inevitable paradox of the large scales
involved is that an ocean that is difficult to imagine being 7 miles deep also can be considered a
"relatively thin" layer on the earth's surface. Students should exercise their understanding of the
paradox, perhaps by debating provocative questions such as "Is the ocean amazingly deep or
amazingly shallow?"
The cause of the seasons is a subtle combination of global and orbital geometry and of the effects
of radiation at different angles. Students can learn part of the story at this grade level, but a
complete picture cannot be expected until later.
Grades 9 through 12
Two important strands of understanding can now be pulled together to enrich students' views of
the physical setting. One strand connects such physical concepts and principles as energy,
gravitation, conservation, and radiation to the descriptive picture that students have built in their
minds about the operation of the planets. The other strand consists of the Copernican
Revolution, which illustrates the place of technology, mathematics, experimentation, and theory
in scientific breakthroughs. In the context of thinking about how the solar system is put together,
this historical event unites physics and astronomy, involves colorful personalities, and raises
deep philosophical and political issues.
National Science Education Standards
Earth and Space Science - Developing Student Understanding
Kindergarten through Grade 4 (Pages 130 – 134)
Young children are naturally interested in everything they see around them--soil, rocks, streams,
rain, snow, clouds, rainbows, sun, moon, and stars. During the first years of school, they should
be encouraged to observe closely the objects and materials in their environment, note their
properties, distinguish one from another and develop their own explanations of how things
become the way they are. As children become more familiar with their world, they can be
guided to observe changes, including cyclic changes, such as night and day and the seasons;
predictable trends, such as growth and decay, and less consistent changes, such as weather or the
appearance of meteors. Children should have opportunities to observe rapid changes, such as the
movement of water in a stream, as well as gradual changes, such as the erosion of soil and the
change of the seasons.
By observing the day and night sky regularly, children in grades K-4 will learn to identify
sequences of changes and to look for patterns in these changes. As they observe changes, such
as the movement of an object's shadow during the course of a day, and the positions of the sun
and the moon, they will find the patterns in these movements. They can draw the moon's shape
for each evening on a calendar and then determine the pattern in the shapes over several weeks.
These understandings should be confined to observations, descriptions, and finding patterns.
Attempting to extend this understanding into explanations using models will be limited by the
inability of young children to understand that earth is approximately spherical. They also have
little understanding of gravity and usually have misconceptions about the properties of light that
allow us to see objects such as the moon. (Although children will say that they live on a ball,
probing questions will reveal that their thinking may be very different.)
Emphasis in grades K-4 should be on developing observation and description skills and the
explanations based on observations. Younger children should be encouraged to talk about and
draw what they see and think. Older students can keep journals, use instruments, and record
their observations and measurements.
Grades 5 through 8 (Pages 158 – 159)
A major goal of science in the middle grades is for students to develop an understanding of earth
and the solar system as a set of closely coupled systems. The idea of systems provides a
framework in which students can investigate the four major interacting components of the earth
system--geosphere (crust, mantle, and core), hydrosphere (water), atmosphere (air), and the
biosphere (the realm of all living things). In this holistic approach to studying the planet,
physical, chemical, and biological processes act within and among the four components on a
wide range of time scales to change continuously earth's crust, oceans, atmosphere, and living
organisms. Students can investigate the water and rock cycles as introductory examples of
geophysical and geochemical cycles. Their study of earth's history provides some evidence
about co-evolution of the planet's main features--the distribution of land and sea, features of the
crust, the composition of the atmosphere, global climate, and populations of living organisms in
the biosphere.
The understanding that students gain from their observations in grades K-4 provides the
motivation and the basis from which they can begin to construct a model that explains the visual
and physical relationships among earth, sun, moon, and the solar system. Direct observation and
satellite data allow students to conclude that earth is a moving, spherical planet, having unique
features that distinguish it from other planets in the solar system. From activities with
trajectories and orbits and using the earth-sun-moon system as an example, students can develop
the understanding that gravity is a ubiquitous force that holds all parts of the solar system
together. Energy from the sun transferred by light and other radiation is the primary energy
source for processes on earth's surface and in its hydrosphere, atmosphere, and biosphere.
By grades 5-8, students have a clear notion about gravity, the shape of the earth, and the relative
positions of the earth, sun, and moon. Nevertheless, more than half of the students will not be
able to use these models to explain the phases of the moon, and correct explanations for the
seasons will be even more difficult to achieve.
Grades 9 through 12 (Pages 158 – 159)
During the high school years, students continue studying the earth system introduced in grades 58. At grades 9-12, students focus on matter, energy, crustal dynamics, cycles, geochemical
processes, and the expanded time scales necessary to understand events in the earth system.
Driven by sunlight and earth's internal heat, a variety of cycles connect and continually circulate
energy and material through the components of the earth system. Together, these cycles
establish the structure of the earth system and regulate earth's climate. In grades 9-12, students
review the water cycle as a carrier of material, and deepen their understanding of this key cycle
to see that it is also an important agent for energy transfer. Because it plays a central role in
establishing and maintaining earth's climate and the production of many mineral and fossil fuel
resources, the students' explorations are also directed toward the carbon cycle. Students use and
extend their understanding of how the processes of radiation, convection, and conduction transfer
energy through the earth system.
Looking outward into deep space and deep time, astronomers have shown that we live in a vast
and ancient universe. Scientists assume that the laws of matter are the same in all parts of the
universe and over billions of years. It is thus possible to understand the structure and evolution
of the universe through laboratory experiments and current observations of events and
phenomena in the universe.
Until this grade level, astronomy has been largely restricted to the behavior of objects in the solar
system. In grades 9-12, the study of the universe becomes more abstract as students expand their
ability to comprehend large distances, long time scales, and the nature of nuclear reactions. The
age of the universe and its evolution into galaxies, stars, and planets--and eventually life on
earth--fascinates and challenges students.
The challenge of helping students learn the content of this standard will be to present
understandable evidence from sources that range over immense timescales--and from studies of
the earth's interior to observations from outer space. Many students are capable of doing this
kind of thinking, but as many as half will need concrete examples and considerable help in
following the multistep logic necessary to develop the understandings described in this standard.
Because direct experimentation is usually not possible for many concepts associated with earth
and space science, it is important to maintain the spirit of inquiry by focusing the teaching on
questions that can be answered by using observational data, the knowledge base of science, and
processes of reasoning.
III. IDENTIFY CONCEPTS AND SPECIFIC IDEAS
Benchmarks for Science Literacy
By the end of the 8th grade, students should know that (pages 68 – 69):
* We live on a relatively small planet, the third from the sun in the only system of planets
definitely known to exist (although other, similar systems may be discovered in the universe).
* The earth is mostly rock. Three-fourths of its surface is covered by a relatively thin layer of
water (some of it frozen), and the entire planet is surrounded by a relatively thin blanket of air. It
is the only body in the solar system that appears able to support life. The other planets have
compositions and conditions very different from the earth's.
* Everything on or anywhere near the earth is pulled toward the earth's center by gravitational
force.
* Because the earth turns daily on an axis that is tilted relative to the plane of the earth's yearly
orbit around the sun, sunlight falls more intensely on different parts of the earth during the year.
The difference in heating of the earth's surface produces the planet's seasons and weather
patterns.
* The moon's orbit around the earth once in about 28 days changes what part of the moon is
lighted by the sun and how much of that part can be seen from the earth-the phases of the moon.
National Science Education Standards
As a result of their activities in grades 5-8, all students should develop an understanding of
(pages 160 – 161):
* The earth is the third planet from the sun in a system that includes the moon, the sun, eight
other planets and their moons, and smaller objects, such as asteroids and comets. The sun, an
average star, is the central and largest body in the solar system.
* Most objects in the solar system are in regular and predictable motion. Those motions
explain such phenomena as the day, the year, phases of the moon, and eclipses.
* Gravity is the force that keeps planets in orbit around the sun and governs the rest of the
motion in the solar system. Gravity alone holds us to the earth's surface and explains the
phenomena of the tides.
* The sun is the major source of energy for phenomena on the earth's surface, such as growth
of plants, winds, ocean currents, and the water cycle. Seasons result from variations in the
amount of the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and
the length of the day.
IV. EXAMINE RESEARCH ON STUDENT LEARNING
Benchmarks for Science Literacy
Shape of the earth
Student ideas about the shape of the earth are closely related to their ideas about gravity and the
direction of "down" (Nussbaum, 1985a; Vosniadou, 1991). Students cannot accept that gravity
is center-directed if they do not know the earth is spherical. Nor can they believe in a spherical
earth without some knowledge of gravity to account for why people on the "bottom" do not fall
off. Students are likely to say many things that sound right even though their ideas may be very
far off base. For example, they may say that the earth is spherical, but believe that people live on
a flat place on top or inside of it—or believe that the round earth is "up there" like other planets,
while people live down here (Sneider & Pulos, 1983; Vosniadou, 1991). Research suggests
teaching the concepts of spherical earth, space, and gravity in close connection to each other
(Vosniadou, 1991). Some research indicates that students can understand basic concepts of the
shape of the earth and gravity by 5th grade if the students' ideas are directly discussed and
corrected in the classroom (Nussbaum, 1985a).
Explanations of astronomical phenomena
Explanations of the day-night cycle, the phases of the moon, and the seasons are very
challenging for students. To understand these phenomena, students should first master the idea
of a spherical earth, itself a challenging task (Vosniadou, 1991). Similarly, students must
understand the concept of "light reflection" and how the moon gets its light from the sun before
they can understand the phases of the moon. Finally, students may not be able to understand
explanations of any of these phenomena before they reasonably understand the relative size,
motion, and distance of the sun, moon, and the earth (Sadler, 1987; Vosniadou, 1991).
Making Sense of Secondary Science: Research Into Children’s Ideas
THE EARTH
Several studies have investigated children’s ideas about the Earth as a body in space. Nussbaum1
and Baxter2 report a possible progression of ideas among American, Israeli and English children,
from a flat Earth with limited sky and an absolute view of ‘down’, to a spherical Earth
surrounded by sky with ‘down’ being towards the centre of the Earth. These findings are
supported by the studies of Nepalese children by Mali and Howe3 and of Californian children by
Sneider and Pulos.4 The work of Vosniadou and Brewer5 with Greek and American children
also cites many similar explanations.
The ideas identified by Nussbaum, Baxter and Vosniadou and Brewer are summarized in Figure
24.1 which shows how similar ideas found by the different studies appear to represent the steps
of a developmental sequence.
Vosniadou and Brewer5 note that some children thought there were two Earths—one flat on
which we live and one spherical in space. Moreover, while many children thought the Earth was
round, at ages 8 and 9 they thought it was round like a plate and that it has an edge. Nussbaum1
suggests that conceptual progress takes place with age or with schooling, such that most 8- and
10-year-olds hold the earliest idea N1, most 12-year-olds hold ideas N2 or N3 and most 14-yearolds hold ideas N4 or N5 (Figure 24.1). Baxter2 suggests that the idea B3 is the one held by most
children whilst the accepted science view B4 is used by less than 20 per cent even at the age of
16. When Nussbaum and Sharoni-Dagan6 evaluated a unit of instruction for 8-year-olds, they
observed that, while 12 per cent of the pupils held ideas N4 and N5 before instruction, 42 per
cent held them afterwards.
Figure 24.1 Children’s notions of the Earth’s shape, sky and the direction of ‘down’
Key: N1–N5: progression of ideas noted by Nussbaum1
B1–B5: progression of ideas noted by Baxter2
DAY AND NIGHT
Vosniadou and Brewer,5 Baxter2 and Klein7 studied children’s ideas about why it gets dark at
night. They suggest a development in children’s thinking with age, from more directly
observable reasons to those involving astronomical movements. (The last two studies also note
that many younger children considered the Sun to be animate.) The children’s notions of day and
night could be seen to fit into four bands of thinking, as shown in Figure 24.2.
Sadler’s study of American 14-year-olds8 identifies the variety of ideas held about the cause of
day and night. He notes that, although over half the interviewed students had taken or were
taking a one-year course, of which a quarter was astronomy, these students did not seem to have
the correct view any more often than the other pupils but they did use many more scientific terms
in their explanations.
Baxter2 identified six ideas about day and night and the prevalence of these is shown in Figure
24.3. It appears that at the ages of 15 and 16 many still hold covering and orbital theories of day
and night.
Figure 24.2 Children’s ideas about why it gets dark at night
Figure 24.3 The prevalence, with age, of pupils’ ideas about day and night
Source: J.Baxter, ‘Children’s understanding of familiar astronomical events’, International
Journal of Science Education 11 (Special Issue): 502–13.
THE EARTH, MOON AND SUN
Although little work has been done on children’s views of the solar system as a whole, three
studies have looked at ideas about the relationship between the Earth, the Sun and the Moon.
Vosniadou and Brewer5 observed a move in children’s thinking with age from an Earth-centered
to a Sun-centered solar system. However, children even at an older age were much less sure of
the position of the Moon.
Jones et al.9 investigated Tasmanian children’s ideas about the size, shape and relationships of
the Earth, Sun and Moon. They too found evidence of a move from Earth-centered to Suncentered thinking, noting the five different models shown in Figure 24.4. Children’s ideas about
the shapes of the Earth, Sun and Moon appeared to change with age: younger children suggested
two-dimensional or non-spherical three-dimensional shapes and older children chose spheres. So
far as the relative sizes of the Sun, Moon and Earth are concerned, there was no apparent trend
towards a correct understanding among older children and far fewer girls than boys chose the
correct model.
Sadler8 observed a lack of understanding both of the relative sizes and the relative distances apart
of the Earth, Sun and Moon. Most pupils drew the three the same size or between half or double
each other’s diameter, and the Sun and Moon were drawn within one to four Earth diameters
away from the Earth. These misconceptions, Sadler suggests, may be compounded, or indeed
caused, by the models used in classrooms or by the diagrams in books, which do not use the true
scale for size and distance.
THE PHASES OF THE MOON AND ECLIPSES
Baxter2 has investigated ideas about the phases of the Moon. He noted five ideas, including the
science view. The four alternative notions involve the covering of (or casting a shadow on) the
Moon by increasingly distant objects (Figure 24.5).
Figure 24.6 shows the prevalence, with age, of the ideas Baxter identified and the dominance of
the ‘shadow of the Earth’ idea even among 16-year-olds.
Baxter’s findings are supported by Sadler8 who found that 37 per cent of his sample attributed
the phases of the Moon to the Earth’s shadow covering the Moon.
Targon10 found that 65 per cent of his sample of university students had no knowledge, and a
further 23 per cent only fragmentary knowledge, of the phases of the Moon; 6 per cent held the
correct notion and 8 per cent had an ‘alternative’ eclipse notion.
Figure 24.4 Models of children’s thinking about the relationship of the Sun, Moon and Earth.
Source: B.L.Jones, P.P.Lynch and C.Reesink, ‘Children’s conception of the Earth, Sun and
Moon’, International Journal of Science Education 9 (1): 43–53.
Figure 24.5 Children’s ideas about the causes of the phases of the Moon
Source: J.Baxter, ‘Children’s understanding of familiar astronomical events’, International
Journal of Science Education 11 (Special Issue): 502–13.
Figure 24.6 The prevalence, with age, of pupils’ explanations of the phases of the Moon
Source: J.Baxter, ‘Children’s understanding of familiar astronomical events’, International
Journal of Science Education 11 (Special Issue): 502–13.
THE CHANGING YEAR
Investigating explanations of the cold in winter, Baxter2 observed an age-related trend in
children’s thinking: from explanations involving nearer and more familiar objects to
explanations involving more distant and less tangible objects, and also the movement of astral
bodies. However, by far the most common suggestion, at all ages, was that the distance of the
Earth from the Sun is the cause of the seasons. Many children believed the Earth is nearer the
Sun in the summer than in the winter and that this accounts for hotter weather in summer. This
idea was also observed by Sadler.8 The prevalence with age of ideas about the cause of the
seasons which Baxter identified is shown in Figure 24.7
Figure 24.7 The prevalence, with age, of pupils’ explanations of the seasons
Source: J.Baxter, ‘Children’s understanding of familiar astronomical events’, International
Journal of Science Education 11 (Special Issue): 502–13.
THE SOLAR SYSTEM AND BEYOND
Lightman et al.11 found that only 55 per cent of adults thought of the Sun as a star and that 25 per
cent thought it was a planet. These researchers note that astronomical literacy is ‘entwined with
social institutions and values, as well as with education’, with younger people, males and bettereducated people having more astronomical knowledge.
VI. CLARIFY STATE STANDARDS AND DISTRICT CURRICULUM
Oregon Standards
Common Curriculum Goal (page 25A):
Understand the Earth’s place in the solar system and the universe.
Content Standard (page 25A):
Explain relationships among the Earth, sun, moon, and the solar system.
Benchmark 2, Grade 5 (page 25A):
SC.05.ES.04 - Describe the Earth's place in the solar system and the patterns of movement of
objects within the solar system using pictorial models.
SC.05.ES.04.01 - Describe Earth's position and movement in the solar system.
SC.05.ES.04.02 - Recognize that the rotation of the Earth on its axis every 24 hours produces the
night-and-day cycle.
Benchmark 3, Grade 8 (page 25A):
SC.08.ES.04 - Explain the relationship of the Earth's motion to the day, season, year, phases of
the moon, and eclipses.
SC.08.ES.04.01 - Explain the relationship between the cycle of seasons and the tilt of the Earth
on its axis.