Enlist a godparent, aunt or uncle. Have them send a message in a very simple code
to your children, with the words "be careful...people want to know what's in this message...it's your job to figure it out" written on the outside of the envelope. Hand the children a TV stone to examine each letter of the code
, which will not help solve the code at all but will make each letter appear in 3-D—adding an extra, cheap layer of wow that works on the same principle as covering a math problem in sprinkles.