What's this Science Bite about?

Make a thaumatrope - your very own optical illusion to wow your friends! Find out how it works.

Remember - if you try this experiment at home you will need the consent and supervision of your parent or guardian.

What you’ll need…

A drawing of what you'll need to make a thaumatrope

  • A piece of card (lighter colours will work better)
  • 2 pieces of string about 30cm long each
  • Colouring pencils
  • A mug or a big circular glass
  • A pair of scissors (please ask an adult to help you with these!!)
  • Blob of blu-tac or plasticine (optional)

How to do this experiment

  1. Take your mug/glass and place it on your piece of card. Draw a circle using your favourite colouring pencil and the mug as a stencil.
    Drawing a circle around the mug on paper

  2. Cut round the circle you have just drawn with your scissors. You may need an adult to help.
    A circle being cut from a sheet of paper with scissors

  3. On one side of the circular piece of card draw a birdcage. On the other side draw a picture of your favourite type of bird.
    A birdcage one one side; a bird on the other.
    IMPORTANT: make sure you draw the birdcage upside-down in relation to the bird.

  4. Get a sharpened pencil and pierce through the card on the left and right hand side of the bird/cage. A piece of blue-tac or plasticine placed behind where you are making the holes may make this easier.
    Making holes in the paper using a pencil and blu tac

  5. Fold one of the pieces of string in half and push it through one of the holes on the card, then push the ends of the string through the loop at the other end and pull it tight. Do the same on the other side.
    Attaching string to the thaumatrope

  6. Hold the thaumatrope far out in front of you with a piece of string in each hand. Twist the strings between your thumb and forefinger until the card spins. This should make it look like the bird is actually in the cage!
    By twisting, it looks like the bird is in the birdcage

Find out more

The retina inside your eye changes the image you see, into electrical nerve signals that are sent to the brain. The image lingers on the retina for up to one-tenth of a second (0.1s). As the thaumatrope spins it switches the images faster than this and it fools your eyes by merging the two separate images into one.

This is called "the principle of the persistence of vision” or “retinal retention.”

Things to Try

Why not try this idea with other pictures? Maybe a picture of yourself on the television or a robber behind bars. Even a plate with some food on it… the possibilities are endless, so get your thinking caps on!

Curriculum Links

Body Systems and Cells

SCN 0-12a/ 2-12a


Glasgow Science Centre