What you need:
Crayon stubs, peeled and broken
Here is what you do... get the old crayons and sort them out.
remove all the paper (the kids can do this!) Then have the kids break them up and put them in a muffin pan one color per cup(or they can mix them up to make rainbow cookies)
Put the pan in the oven at 150 degrees for 15 to 20 minutes but watch them and remove them when the crayons turn mushy but are not melted completely yet.
Then you put them in the freezer for 1/2 hour so they get hard and they will pop out easily!