This was our culminating activity for our States of Matter Science unit.  We measured and broke old crayons into one-inch lengths.  Then, we sorted by color and placed them in lined muffin pans.  We baked them at 175 degrees for about 20 minutes, then took them out to cool overnight.  The next morning, we unwrapped them and tested them out.  Solid, then liquid, and back to solid again.  Science can be colorful!