The teacher explains how the earth goes around the sun while Atlas and Helios demonstrate. Atlas walks around Helios while Helios keeps the flashlight pointed straight at the earth. The two should stand no further than 5-7 feet apart. Have Atlas stop when the purple person can see the sun. Ask Atlas if he/she can tilt the earth so that the sun is directly overhead of the purple person in the north. The rest of the class can help Atlas. Ask: "Is the sun bright or more direct for the purple person or the pink person? Do you think it is hotter for the purple person or the pink person?" Refer to Direct/Diffuse Light Lesson if needed. Now ask Atlas to tilt the earth so that the sun is directly overhead of the pink person. Ask: "Is the sun brighter or more direct for the purple person or the pink person? Do you think it is hotter for the purple or the pink person?"
While Atlas has the sun over the pink persons head, the teacher helps the class find the point to which the north pole points in the classroom (wall, ceiling, etc.). Teacher tapes the black circle on the wall or ceiling as a reference point. Ask Atlas to orbit the sun (walk around the flashlight) keeping the north pole pointing at the black circle. Remember to have Helios keep his light pointed at the earth. Have the rest of the class help make sure Atlas doesn't change the tilt of the earth. Have Atlas stop after one-half of an orbit so that he is opposite of where he started. As the earth is orbiting the teacher explains that the earth is tilted one way and stays tilted the same way all the time.
Ask a volunteer to come up and make it daytime for the pink and purple people. It should be night for them if Atlas has orbited correctly so the volunteer will have to spin the earth. Ask: "Is the sun more direct on the purple person or on the pink person? Is it hotter for the purple person or the pink person? Is it summer time or winter time for that person? (summer for the purple person) Is it summer or winter for the pink person?"
Now have Atlas orbit the sun halfway around again making sure to keep the north pole pointed at the black circle. Ask a volunteer to make it daytime for the purple and pink people. Ask: "Is the sun more direct on the purple or the pink person? Is it hotter for the purple or the pink person? Who is it summertime for? Wintertime? How do you know that? Is the sun brighter or more concentrated for the person who is in summer or the person who is in winter?"
At this point it is a good idea to point out that the seasons are opposite for people on the top (north) of the earth and on the bottom (south) of the earth. Ask: "When it is winter on the top (north) of the earth, what season is it on the bottom (south) of the earth? When it is winter on the bottom (south) of the earth, what season is it on the top (north) of the earth?" Teacher should repeat the orbit model as often as necessary, giving other volunteers the earth/sun responsibilities.
Remove the pink person. Ask the students: "When is Autumn?" (refer to the sequence of seasons on the chalkboard; in between summer and winter) Have the class help position the earth so that it is summertime for the purple person, remembering to keep the north pole pointed at the reference point. Ask Atlas to orbit slowly toward the winter position. (Teacher and class can help.) Ask the class to help Atlas stop when it is autumn, halfway between summer and winter. Ask a volunteer to point on the globe where the sun is most direct. (equator) Have Atlas continue orbiting to the winter position.
Ask the students: "When is Spring?" (refer to the sequence of seasons on the chalkboard; in between winter and summer). Ask Atlas to orbit slowly toward the summer position for purple person. Have the class help Atlas stop when it is spring for the purple person, halfway between winter and summer. Ask a volunteer to point on the globe where the sun is most direct (equator). Teacher should repeat this model as often as necessary giving other volunteers the chance to be Atlas and Helios.
Divide the class into four groups. Pass out one earth model, one thumbtack and one flashlight to each group. If there are not enough flashlights available, then one group member can hold a yellow colored styrofoam ball which will represent the sun. Have a member of each group push the thumbtack midway between the equator and a pole. Explain that the thumbtack represents a person. Have the groups practice modelling the different seasons. Allow enough time for each group to practice so that they will be able to model the different seasons for the rest of the class.