With the special granulate and the various molds, kids aged 8 to 12 can mix their own round and square bouncy balls in a variety of colors. Especially cool is the glow-in-the-dark bouncy ball, which shines brightly in the dark. When it gets a pair of googly eyes, it becomes really fun. Once the first balls have dried out after a few days and lost their bounce, new ones are needed. Luckily, the granulate in this set is enough to make up to 20 power balls. Exciting info texts and fun facts explain why some colors glow in the dark and how, for example, deep-sea animals take advantage of this.