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Make a science spinner

This activity will take 30 minutes, is for ages 7 to 10 with supervision needed.

Make a mini movie and trick your brain into seeing something that isn’t there.

When you look at something, your eyes send the information of what you see to your brain. Your brain can only process this information at its own speed and when things move too quickly, it can make mistakes.

A thaumotrope is a spinning toy invented way back in the 1800s. It tricks your brain into seeing two different images together as one image. This is how videos trick your brain into seeing a many separate images as a moving picture. 

What you'll need

  • Card or thick paper
  • A glass
  • Two 50cm lengths of string
  • Colouring pens or pencils 
  • Scissors
  • Blu Tack
  • Glue

Step by step

  • Draw a circle

    Step 1 of 7

    Someone holds a drinking glass in one hand and a pencil in the other hand. They are drawing around the glass to draw a perfect circle on a piece of paper

    Carefully cut a circle and two smaller circles out of your card. You could draw around a cup to help you draw your circles.

  • Poke holes

    Step 2 of 7

    Using a pencil tip, two hands poke two holes either side of a cardboard circle

    On the left and right side of your larger circle, poke pairs of holes about one centimetre apart.

  • Thread string

    Step 3 of 7

    Two hands thread string through two holes on either side of a cardboard circle

    Thread some string through one pair of holes and tie a knot. Repeat with the string through the other holes.

  • Plan your design

    Step 4 of 7

    Two hands stick a fish tank on a circle

    Plan your design on some scrap paper. Your two pictures should combine to make one image.

  • Draw your design

    Step 5 of 7

    Three circles on a table, one has string threaded on either side, one has a picture of a fish and the other has a picture of a fish tank

    Draw your design on each of the smaller circles. 

  • Glue your designs

    Step 6 of 7

    Two hands stick a fish tank on a circle

    Glue your designs on either side of the larger circle. One side needs to be upside down for the illusion to work.

  • Spin and see

    Step 7 of 7

    Two hands spin a circle that has a fish and a fish tank on either side

    Holding the strings in each hand, spin the disc around like a skipping rope. When the string is twisted up, pull them tight and the disc will spin, creating your illusion.

Fun facts

This illusion helps us understand how your brain works. Your brain receives information from your sensory organs such as your eyes and nose. These organs send information through a network of nerve cells called your nervous system. Your nervous system can send messages quickly, but when objects move too fast, your brain can get confused.

When your thaumotrope spins slowly, your eyes and brain can easily work out there are two images. When it spins faster your brain can’t keep up. In its confusion, your brain interprets the two rapidly changing images as one.

As well as receiving information from your senses, your brain makes predictions about what it expects will happen based on your past experiences. These two sources of information combine to create what you see. 
 

Crick scientists

Here at the Crick, scientists are finding out how the brain and the nervous system work. They’re studying what’s different in the brains and nervous systems of people living with certain diseases. This will help us treat those diseases and make people feel better. Learning how nerve cells work and why they sometimes don’t work might also help us prevent and treat diseases like Alzheimer's and Parkinson's.

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