3 in 1
Magician shows his hands to be empty.
For his next trick he needs three sponge balls. Suddenly one appears in his right hand and two appear in his left hand, the third in his pocket, asking the spectator how many he has in his hand, they answer "two".
He says, "I have only one in my hand", whereupon he opens his hand and out pops a large cut out of the number "1".
Great way to illustrate the Trinity as well as other Gospel lessons.