Phases of the Moon: Oreo Cookies

Use Oreo cookies (Double Stuff work best for this exercise)  to model the phases of the moon. 

Split the cookies open and scrape off the appropriate amount of cream filling, so you're left with the desired "picture" of the moon.

You could use a whole bunch of these and create the whole cycle.  Use some frosting to "glue" the cookies to a plate in the appropriate order.

Or, you could use it as a quick, fun assessment - give each student one cookie and have them pick one of the moon phases out of a hat.  They then need to use the cookie to illustrate the phase they selected.