Yesterday the Astronomy class I am working with was covering the phases of the moon. I suspect that a lot of people in society don't really understand why we have phases of the moon. Contrary to popular belief it is not the Earth blocking out sunlight from the moon. In fact, it is just where the moon is in relation to the sun and the Earth. Basically, half of the moon is always light and half is dark, there are phases because from our vantage point on Earth we see only a certain amount of the light or dark sides at any given time. To get a visual:

{image}

Notice in the inner circle each moon is half lit by the sunlight (coming from the right side of the picture). You can see the phases we see at each location of the moon though. This is a good time to clear up any misconceptions your students have about the moon!