The Earth turns on its axis. The Moon turns on its axis. The Moon orbits around the Earth. Clouds cover the Moon.
I gave my students this multiple choice question: The shape of the moon appears to change regularly during each month. Which of the following best explains why the shape of the moon appears to change?

Only one answer is correct among these 4 choices:
- The Earth turns on its axis.
- The Moon turns on its axis.
- The Moon orbits around the Earth.
- Clouds cover the Moon.

Could you tell me which one is correct?

The Moon orbits around the Earth.