cartoon robot



This demonstration gives the illusion of mind reading using properties of odd and even numbers!


  • Sticky note pad
  • Pencil or pen


  • Display the set up to the participant/s with the sticky notes all of a single colour in a 3×3 square and explain to them the setup.
  • Explain that they will be starting from the top left-hand sticky note, and you, the instructor, will be counting up incrementally out loud. With each step counted, the participant/s will move from one sticky note to the next in their minds horizontally or vertically but NOT diagonally. It is important that the participant/s do not disclose which sticky note they are on.
  • Then, you as the demonstrator shall remove one sticky note at a time, and will eventually guess their location by narrowing their position down to 1 remaining sticky note.
  • Begin the demonstration, and by implementing the trick, remove sticky notes with every count.
  • Repeat this until you have narrowed down the participant/s to a single sticky note.
  • Ask the participant/s whether they can guess how you have done it.
  • Allow them to observe the set-up and see if they notice what the trick is.

Spark Creative Learning!

At no time will the demonstrator know where the participants are on the 3×3 square of sticky notes. Here’s the trick: the 3×3 sticky notes can be visualized in the mind of the demonstrator as having alternating colours – similar to a chessboard. Since the participants can only move in lateral directions if they were to move an even number of moves they don’t change colour. But were they to move an odd number of moves, they would change coloured squares. With this fact, the demonstrator may remove squares one a time that they know the participants are not on until 1 square remains.

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