Lunar Phases
Lunar Phases is the changing shape of the lit part of the Moon as it circles Earth each month.
Hold a flashlight on one side of a ball in a dark room. Walk around the ball slowly. From your side, the lit part changes shape. It goes from a full circle to a half circle to a thin sliver. That shifting lit face is what we see when the Moon orbits Earth each month.
Explaining lunar phases by grade level
The Moon does not make its own light. The Sun shines on it. As the Moon moves around Earth, you see different parts of the lit side. That is why the Moon looks like it changes shape each night.
Projects that explore lunar phases
Each night the Moon reveals a different sliver of its sunlit half. As the Moon orbits Earth, you can watch the crescent grow from new Moon to first quarter, then keep growing until the full lit face appears. After that, it shrinks back through the same shapes in reverse — waxing on one side, waning on the other.
The Moon does not change shape as it circles Earth. You just see different amounts of its sunlit side. Cookie models show this well. The white filling stands for the sunlit part. You scrape filling to match each phase, from none at new moon to all at full moon.