Why does the moon appear to change shape during the course of a month

The shape of the moon depends on its position around the sun and the different phases.

Explanation:

As the Moon navigates around the Earth, sunlight is reflected.

From Earth, only a part of the moon is visible to us.

The shape of the Moon we see on at night depends on the amount of sunlight is in the face of the moon during its cycle.

The shapes of the Moon are called phases. These phases occur during the Lunar Cycle, which lasts about 27 days.

The Moon is between the Earth and the Sun when the Lunar Cycle begins.

During this phase, the part of the moo reflecting rays from the Sun isn't visible on Earth, so the moon isn't seen at all. This is called New Moon.