3 Shell Telepathy Cards

Effect

Three cards, each with a walnut shell printed on its back and only one with a pea on its front, are explained, then put into envelopes and mixed by a spectator. No matter how well the envelopes are mixed, the performer can always locate the pea! Everything is examinable and immediately repeatable! No reset! Easy to do!

*Includes a bonus routine where all the cards are shown and there is no pea, then a pea is shown under every shell! Finally, the cards are honestly shown, then placed in envelopes (so they can't be manipulated), and finished as above.