This is one of my favorites—I use it in just about every kid show I do. I like to use it early in the show, as an eye test. Pass a red sponge ball between your hands, and have the kids guess which hand has the ball. Try it again, but this time the kids catch you sneaking the ball into your pocket. Finally, pass the ball back and forth between your hands, and have the kids make one last guess. Open one hand, and the red ball has turned black! The kids catch a flash of red in your other hand, but it turns out to be a cube. The red ball is then found in your pocket. Made by Goshman. Color Changing Ball to Square is only $5.