Varinha (preto para vermelho em mudança da cor)

You hold a black color wand in your hand and try to do some magic. The magic doesn’t happen since you need a red color wand to do it.So you pass your hand over the wand and presto, it changes into a red color wand. Since you don’t want the wand to do magic on it's own you pass your hand over it one more time and it changes back into a black wand.You may even spin the wand to show that it is absolutely normal. This can be repeated any number of times.Very visual and very easy to do.