As you learned on the Help Me I Think I'm Changing page, each month the moon seems to change how it looks. Changes in appearance are called the phases of the moon.

Remember that the lighted side of the moon must always face the sun. The difference of which phase you see on earth is due to the moon's position as it revolves around the earth.

Try It!

Demonstrate how the sun, moon, and earth are related as follows:

Materials:

• Three people
• One sign for each person in each group labeled  sun, Earth, and moon

Procedure:

• The first person acts as the moon. This person is to slowly walk in a counter-clockwise circle around the person acting as Earth. As the moon person walks around the "Earth" person make sure the moon's face is always looking at the Earth person.
• The Earth person is to turn counter-clockwise and revolve around the sun at the same time.  Walk them through this several times before letting them do it on their own.
• The last person acts as the sun. They stand in one place and do not move.
• Divide the class into groups of three and have each group demonstrate as the teacher walks around checking each group.
• Change roles with your friends and repeat until everyone has taken the part of the moon, sun, and Earth.

Analysis

• Draw the positions of the sun, Earth, and moon when the person acting as the moon is in the position of the four main phases.

• Describe the orbit of the moon around Earth in relationship to the orbit of the earth as it orbits the sun.