A beautiful 15″ x 11″ picture frame with a black and white picture of a Christmas tree is shown to the children. The following story is told… Twas the night before Christmas and the Christmas tree wasn’t decorated yet Santa was coming and the stores were all closed. So I took out my magic scarf with all its beautiful colors and magically waved it at my plain black and white Christmas tree. Lo and behold, the tree was instantly decorated with all beautiful colors and my magic scarf was black.

You can do the above effect or make up any story where a black and white picture magically turns to a full colored picture.