Cover the work area with a plastic tablecloth to protect it from the paint. Set up several disposable plates; use one per paint color you wish to create. Squirt 1/2 cup or so of shaving cream onto each plate, or allow the kids to do it to experience the fun themselves. Add in an equal amount of school glue; exact proportions are not necessary, and the paint will still puff up and dry even if the proportions are somewhat off. Stir the mixture gently with a foam brush or plastic spoon, but keep stirring to a minimum so the foam stays fluffy. If creating colors, add a drop or two of food coloring to the ingredients before stirring, adding more for deeper colors.