Sometimes the play becomes so much fun that others will want to join in as additional characters or as the audience. If the experience proves to be a good one, you can look for additional storybooks that can be acted out. Any kid can tell you it's to play with. Slowly add cornstarch, mixing it with your hand. Add enough cornstarch so that the slime looks wet when you're pouring it, but feels dry when it is touched.
Children can do the mixing with some supervision.
Color can also be added. The best way is to add powdered tempera to the cornstarch before mixing, or you can add food coloring to the water before mixing. Kids get bored with the same thing day after day. Here's how to make an apple sandwich. Core an apple and slice it into rings.