Magician shows a slate with 6 cards face down, clipped 3 on each side. A spectator is asked to select a card. It is taken out and placed in the holder at the top of the slate, back of the card towards the audience. When the magician turns the slate around, the audience sees the selected card matches the predicted card written on the slate. Complete with Slate, Cards and Instructions.

Slate of Mind Wooden (watch video)