Modeling Earth’s Tilt Assignment Summary
Background Information
The cycle of seasons is caused by Earth's tilt toward the Sun. Earth makes a complete orbit around the
Sun every 365.25 days. It spins on an invisible axis that is tilted at an angle of 23.5°. The angle does not
change; only the direction of the axis in relation to the Sun changes.
The north end of the axis points away from the Sun for half of year and toward the Sun for the other half.
Depending on the time of year, some parts of Earth are tilted more toward the direct rays of the Sun than
other parts. Parts of Earth that get more direct rays get warmer, and parts that get fewer direct rays are
cooler. The difference in the amount of heat and light available at Earth’s surface determines the
seasons.
Seasons vary from one part of the world to another. At different times during the year, the Northern or
Southern Hemisphere is closer to the Sun. When it is summer in the Northern Hemisphere, it is winter in
the Southern Hemisphere. When it is winter in the Northern Hemisphere, it is summer in the Southern
Hemisphere. Both hemispheres get similar amounts of energy from the Sun during fall and spring
iii. Find the approximate latitude of your current location and draw a dot on the ball. For
example, if you live in Chicago, which is at about 40° north of the equator, you would
draw your dot slightly less than halfway between the equator and the North Pole.
iv. Poke a hole in the plastic cup with the metal skewer. Be sure that the hole is large
enough for the skewer to rotate in it. See illustration 2 for further guidance.
v. Cut off a three-inch piece of tape and paste in its center a one-inch piece of tape (sticky
sides together). Place the skewer into the hole in the cup and use the tape to hold the
skewer against the side of the cup. Your model should have an angle of about 23.5°. See
illustration 3 for further guidance.
vi. Turn on a lamp or flashlight, which serves as the Sun. Choose a visual reference as the
North Star and make sure the axis of Earth model points to the North Star at all times.
Darken the room, or move to an area that is already dark.
b) Create a model showing how Earth’s rotation on its axis causes day and night (individual activity).
i. Rotate the model counterclockwise one full rotation. You should notice that the dot is in
light (day) for about half of the rotation and in shadow (night) for the other half of the
rotation.
c) Create a model showing how Earth’s tilt causes seasons and regional climates (group activity).
i. Form groups of four.
ii. Have each person in the group stand in one of the seasonal positions around the center
light in the darkened room: December 21, March 21, June 21, and September 21. See
illustration 4 for further guidance.
iii. Have the person in each position make a complete rotation of his or her model, making
sure the axis points to the North Star at all times during the activity.
iv. The person at each position should report the following: what fraction of the day his or her
dot is in the light and whether the Sun strikes the dot directly or at an angle.
Step 4: Create a typed paper describing models.
a) Type several paragraphs describing how your models showed the effect of the rotation of
Earth on day and night and the effect of Earth’s tilt on seasons and regional climates.
i. Discuss all components of your model and the group activity, as outlined in step 3.
ii. Describe what you observed about darkness and light with your model.
iii. Describe what you discovered about the seasons and regional climates in the group
activity.
b) Make sure your paragraphs include correct sentence structure, punctuation, grammar, and
spelling.
c) Ask your teacher where you should save your work. Your teacher also may have specific
Step 5: Evaluate your project using this checklist.
If you can check each of the following boxes, you are ready to submit your project.
 Is your name on your model?
 Did your model show the equator, the latitude of your city, and the 23.5° tilt of Earth’s axis?
 Did your model depict the effects of the Sun on Earth during a complete rotation?
 Did the group activity show how the tilt of Earth on its axis determines the seasons and regional
climates as it orbits around the Sun?
 Did you write several paragraphs describing the results of your experiment? Did you discuss
all components of your model and the group activity in this paper?
 Did you double-check for correct sentence structure, punctuation, grammar, and spelling in your
paper?
a) If you were unable to check off all the requirements on the checklist, go back and make sure
that your project is complete. Save your project before submitting it.
b) Turn in your model to your teacher. Be sure that your name is on it.
c) Submit your typed paper through the virtual classroom.
d) Congratulations! You have completed your project.