Sidewalk Chalk

1 cup plaster of Paris (do not pack)
Almost 1/2 cup cool water
Liquid Tempera paint (various colors)
Margarine tubs or other disposable mixing containers
Disposable molds (toilet paper rolls with tape covering one end)

Pour plaster into a container. Using a disposable stick, stir in most of the water. Add 2 or 3 tablespoons of liquid tempera, mixing well, especially at the bottom. Add a little more water so the mixture thickens, stir well, and pour into the molds. Remove the molds after the chalk is completely dry.