The green ball will change the red balls to blue balls or the blue balls to red balls. Add a ball with the + ball. Change the speed that the new ball will cause a sound to happen by clicking on the faster or slower purple balls and then hit the + ball. Red balls will stay in the circles until you move them. Blue ones will not. Wow that was confusing! Really, just experiment with it. You can either play with drum sounds or piano sounds. Warning! This will probably annoy adults.