Probably the most simple mental feat ever devised, yet one of the most effective! Three cards are placed on the table face up. One has a red spot, one has a yellow spot, and the last a blue spot. The spectator now makes an absolutely free choice of one color.
He can even change his mind. No matter which color is chosen, the Magi produces a prediction that matches the chosen color. Prediction is in full view of the audience during the entire effect. Everything you need, including pencil.