Earth’s Seasons
Time Allotted: Two 45-minute periods
Indiana State Standards
6.3.5 Use models or drawings to explain that the Earth has different seasons and
weather patterns because it turns daily on an axis that is tilted relative to the
plane of the Earth’s yearly orbit around the sun. Know that because of this,
sunlight falls more intensely on different parts of the earth during the year (the
accompanying greater length of days also has an effect) and the difference in
heating produces season and weather patterns.
Objectives


Participants will be able to use a model to describe the amount of sunlight falling
on the Earth’s surface at different times during a year.
Participants will be able to explain that the seasons are caused by the tilted axis
and the angle of sunlight on the surface of the Earth.
Materials:
Part 1
 Earth-Moon apparatus (polystyrene base (1), polystyrene ball (1), bamboo
skewers (1)) – 1 per group
 Thick book – 1 per group
 Calendar with equinoxes and solstices or seasons marked – 1 per group
 Part 1 Earth Seasons Handout and Questions – 1 per student
 Floor lamp (2)
 Globe (1)
Part 2
 Thermometer – 1 per group
 Stopwatch – 1 per group
 Black construction paper envelope (2”x4” and stapled) – 1 per group
 Lamp – 1 per group
 Ring stand – 1 per group
 Beaker – 1 per group
 Ice cubes – Enough to fill half of a beaker per group
 Part 2 Earth Seasons Handout and Questions – 1 per student
Earth Seasons Ver. 1.0
Background:
This lesson has two parts that help to explain the different seasons experienced
throughout the year. The causes of the climates of different areas are not intuitive. A
common misconception is that the Earth is closer to the Sun in the summer and further
away in the winter. In actuality this is untrue, for the northern hemisphere the Earth is
147.5 million km away from the Sun in summer and 152.6 million km away in winter
(Phillips, 2005). These distances are so great that it is not actually the heat of the Sun
affecting the Earth. Another misconception of those living in the northern hemisphere is
that temperatures get colder as one travels north, but for those at the equator if you
traveling south the same happens. Unlike cold temperatures at higher altitudes
(mountains), cold temperatures at higher latitudes are not easily explained. The cold
temperatures are caused by the angle in which the sunlight hits the surface of the earth.
At the equator the sun is overhead and light directly impacts the surface making it hot.
At the poles the angle of the sunlight is almost parallel with the surface. This indirect
light causes the higher latitudes to remain cold and not heat up. This is only part of the
reason that the Earth experiences a different seasons.
The seasons of the Earth are also controlled by the more direct sunlight received in a
hemisphere during the yearly orbit due to the tilt of the Earth’s axis. The axis of the
Earth is tilted at about 23.5º and it constantly points in the same direction, the North
Pole towards Polaris (the North Star). It is easier to think of the Earth as a spinning top
on the floor of a room (WU, 2000). Imagine that in the center of the room is the Sun
and the top circles around it, or orbits. As the top circles the room it remains tipped
toward one of the same wall at all times. This means that some times the top’s bottom
is more exposed to the Sun during part of orbit and the top’s top is more exposed at the
other side of the orbit (WU, 2000).
Like the top, when the northern hemisphere is tipped toward the Sun, the sunlight is
more direct causing the summer season. Meanwhile, as the northern hemisphere is
pointing towards the Sun, the southern hemisphere has less light and experiencing the
winter season. The two hemispheres experience the opposite season throughout the
year because of tilt of the Earth. If the Earth did not have a tilted axis, seasons would
not exist. The angle of light would be constant and so would the climate. The equator
would be hot, the poles cold, and the middle latitudes would some where in the middle
never changing and never changing seasons. Please see the following websites for
more information and diagrams.
The following websites are a good review/overview of the Earth’s seasons:
http://www.rcn27.dial.pipex.com/cloudsrus/seasons.html
http://www.windows.ucar.edu/tour/link=/kids_space/why_seasons.html&edu=high
The following websites have good information, but are of a more technical nature:
http://library.thinkquest.org/29033/begin/earthsunmoon.htm
http://www.ecology.com/ecology-today/tilting-earth/
http://science.nasa.gov/headlines/y2000/ast30jun_1m.htm
Earth Seasons Ver. 1.0
Procedure
Engage: (10 min)
This engagement activity relies upon the students conveying their personal experiences
of the different areas they have traveled and the previous knowledge students have of
the climates around the Earth. There are two parts to this lesson, but each activity
requires a similar engagement if both are not done.
 To start the discussion, have students divide into groups with one student acting
as the recorder. Have students list all the other states and countries they have
visited. Also on the list have the recorder put the time of visit (ex. month or
season) and the weather/temperature.
o If students have not been out of state, have them assemble a list of places
they have heard about and the weather/temperature they would expect
there during different times of the year.
o Try to steer students away from hot, cold, warm references and have them
use references in relation to the city they currently live. (Ex. South
Carolina in July was hotter than Indianapolis in July) This will allow for
easier comparison between different sites.
 Have each group give their locations that are furthest north and south and write
them on the board with the weather/temperature descriptions.
o Ask if the students see a trend in the data?
o If no trend is present, ask the following:
 What happens as you go south or north? Students should respond
that near the equator is hot and that near the North Pole is cold.
o A generalized response should be “If you go north it gets cold, if you go
south it gets warm.”
 After getting something similar to the generalized response above have students
explain the following:
o Why are northern areas colder?
o Why is Antarctica cold if the generalized statement is true?
o Are the seasons for North America the same for South America or
Australia? What causes the difference?
o What causes the seasons?
 Start to discuss the differences in timing for the seasons in the Northern and
Southern Hemispheres. That winter for the Northern Hemisphere is the summer
for the Southern. Also introduce that the Earth’s axis is tilted about 23.5º and the
top always points in one direction.
Assemble the Earth-Moon apparatus and demonstrate its use to the students. Review
the concepts of one rotation equaling a day, one revolution around the sun equaling a
year, sunrise, sunset, daytime, nighttime. Also use a standard globe to compare it to
the Earth-Moon apparatus
Part 1:
Explore:
Setup for this part consists of the following:
Earth Seasons Ver. 1.0
1. Setup the room like the figure 1. This allows for eight groups of students to work
on the Part 1 activity at the same time.
2. Make the desks near the front of the room position 1 and label the others as in the
figure 3.
Activity:
Desk
1
1
1. Assign students to groups at
the different positions and
pass out the Earth-Moon
2
4
2
4
apparatus (Figure 2)
materials and the Part 1
Lamp
3
3
Handout and Questions.
2. Instruct the students on the
assembly of the Earth-Moon
Figure 1: Room Setup for Part 1
apparatus. The final result
should resemble Figure 2. Help the students draw the equator, North Pole (N),
South Pole (S), and a rough dot at the latitude they live as a reference point. Have
the students tip the apparatus toward the front of the room with the help of a thick
book.
3. Turn on the lamps and have students record the side of the Earth lit up by the
“Sun” (lamp) for each station on the Part 1 handout as the students circulate the
stations in a counter clockwise direction
with their Earth-Moon apparatus.
Front of
Room
Explain:
1. In the groups have students assign each
position a season for the northern
hemisphere and the calendar date
BOOK
associated with each. After they decide
have the groups present the assigned
seasons for the four positions. Use this
Figure 2: Earth-Moon Apparatus
time to discuss the positions and give the
students the correct answers to the positions. The seasons match to the following
positions: 1-Winter, 2-Fall, 3-Summer, and 4-Spring.
2. In the discussion have the students answer the following for the northern
hemisphere:
a. Why is winter cooler than summer?
i. Answer thus far: (During winter the northern hemisphere is exposed
to less light than the southern causing winter.)
b. What causes the seasons?
i. Answer thus far: (The tilt of the Earth causes more light to fall on
different parts of the Earth causing the seasons.)
3. After the students have recorded all four stations, have them answer the questions
for Part 1. Students may require help answering the questions and this part could
be more of a group discussion. Answers to the questions are at the end of this
packet.
Earth Seasons Ver. 1.0
Part 2:
For this part of the lesson students need to be familiar with reading the thermometers
that will be used. If necessary review the procedure and units the thermometers
measure. To set up for Part 2 cut and assemble square black envelopes out of black
cardstock and staples, enough for each group.
Explore:
Hand out the Part 2 worksheet, questions, thermometers, black envelopes,
stopwatches, ring stands, beakers, ice, and lamps to each group of students.
It is important when getting started that you help students make the conceptual leap that
they are simulating the sun and the surface of the Earth. To make it easier set up a
lamp and globe and put a thermometer on the surface. Move the thermometer over the
surface of the globe to show the different angles as the thermometer moves from the
equator to the poles. Also, use the Earth-Moon apparatus to demonstrate the different
angles the thermometer and lamp make for the different seasons.
Instruct the students in the set up of the equipment or have it done prior to beginning.
Have the students follow the directions and the diagrams on the Part 2 worksheet and
record their data on the provided Temperature Data Table. To save time different
groups can run different trials and then share data. After the data is collected have the
students graph the three different trials to compare the temperature increases.
Explain:
Have the groups present the results of the three trials. Have the students identify which
trials correspond to the different places on the Earth. Identify that the trial that heated
up the fastest was caused by the direct light on the flat envelope. Have the students
answer the questions for Part 2. These questions can be used in the discussion to
relate the Part 2 activity with the seasons.
Elaborate:
Discuss the two factors that cause the seasons. Have the students figure in the amount
of light in a day and the seasons. In this discussion have the students figure out the
reason the North Pole does not get hot even though it gets 24 hours of light in the
summer. If needed set up the Earth-Moon apparatus again and demonstrate the 24
hours of light. Students should identify that the tilt of the axis and the angle of the
sunlight at different times of the year causes the seasons for the Earth.
References:
Philips, T., 2005, http://science.nasa.gov/headlines/y2000/ast30jun_1m.htm
Windows to the Universe (WU), 2000,
http://www.windows.ucar.edu/tour/link=/kids_space/why_seasons.html&edu=high
Earth Seasons Ver. 1.0
Questions and Answers:
Part 1
1. When did the Northern Hemisphere receive the most light? What was the
Southern Hemisphere like at this time?
Position 3, Southern Hemisphere had very little light
2. When did the Southern Hemisphere receive the most light? What was the
Northern Hemisphere like at this time?
Position 1, Northern Hemisphere had very little light
3. Are there times when both northern and southern hemispheres receive the same
amount of light? When do these occur?
Yes, Position 2 and 4
4. When does the equator receive the most light?
All positions
5. Do you think that there is a relationship to the amount of light received and the
temperature?
Yes (This should be the answer prior to completion of Part 2)
6. Do you think that there is a relationship between the amount of sunlight and the
season? Given your answer, which positions correspond to which seasons?
(Again this answer is answered before Part 2, have students answer for the
Northern Hemisphere) Yes; Position 1 = Winter, Position 2 = Spring, Position 3 =
Summer, Position 4 = Fall
7. How much light does the North Pole get in the summer? Why is the North Pole
not hotter than the equator?
24 hours. Any answer that tries to explain the second part of this question
should be accepted. Without completing Part 2 the correct answer is not known.
If you would like hold this question until Part 2 is complete.
8. What is causing the seasons?
Thus far the answer should be: The Tilt of the Earth.1
Part 2
1. Which trial showed the greatest temperature increase?
Flat Trial
2. What causes the differences in the temperature increases between the trials?
Angle of light
3. Which trial best represents the way sunlight strikes the equator?
Flat Trial
4. Which trial best represents the way sunlight strikes the poles?
Standing Trial
5. What parts of the globe would the remaining trial represent?
Mid-latitudes OR half way between equator and the poles
6. Why is the equator always hotter than the poles?
Angle of sunlight is more direct, unlike the poles, which are more indirect
sunlight.
7. Why is the northern hemisphere hotter in July?
More direct sunlight and more sunlight
8. Why is the southern hemisphere colder in July?
Less direct sunlight and less sunlight
9. What two things cause the Earth to have seasons? (Hint: Look at Part 1 and Part
2 of the Earth Seasons handouts.)
Angle of sunlight and tilt of the Earth’s axis
Earth Seasons Ver. 1.0