This simple but wonderous mixture of constarch and water fasinates children. As they pat and squish it, the mush changes magically from dry to wet and from hard to soft. In each of three bowls, stire together a batch of mush by combining 4 cups of cornstarch with 1 cup of water. You also can add a couple of drops of food coloring or glitter to give each bowl a special shade. Set up chairs at a table covered with newspaper or plastic tablecloth and provide smocks and wet washcloths to keep participants tidy. Magnificent Mystery Mush is non-toxic, but it's not for eating -- tell the kids they can play with it, but they shouldn't put it into their mouths.