Make an optical illusion

This optical illusion lets you turn two pictures into one. Did you know your brain uses short cuts in order to process all the millions of things we see at any one time. An optical illusion “tricks” your eyes and brain.

What you need:

  • white cardboard
  • pencils and colouring pens
  • scissors
  • glue/sellotape


  • Cut out two shapes from a sheet of white cardboard.
  • Draw whatever you want, but we tried some fish on one piece and the tank on the other.
  • Glue or sellotape a pencil in between the two pictures.
  • Hold the pencil between your palms and rub your hands to make the picture spin around.



The Science bit

The fish should look like they are inside the tank.

This is the same concept used for making cartoons, still pictures are moved very quickly to create an illusion of movement.

There are 20 comments

  1. Ross Mannell

    This is an old favourite. When the flicker rate is high enough, the brain starts to blend the two images so we see the bird in the cage. Wonderful. How sad it would be if this were not so. Seeing a movie would become a series of still images.
    Ross Mannell (teacher)

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