How do films work?

How do films work?

Make your own optical illusion to show how movies work!

A thaumatrope - a type of optical illusion - makes two images appear as one.

For example a picture of a cage and a picture of a lion will turn into a picture of a lion in a cage!

What you need:

  • Thaumatrope template - draw your own or download the one in the video from Questacon - tricky pictures (pdf).
  • Scissors
  • Black pen or coloured felt tips
  • Skewer (you could use a pencil or a straw instead)
  • Sellotape
  • Pen

How to:

  1. Use the thaumatrope template from Questacon - tricky pictures or draw your own. You can use any pictures that go together. How about having hair and a smile on one side, and a nose and eyes on the other side?
  2. Cut out the template and fold it in half, with the pictures on the outside.
  3. Tape the skewer inside the template, with one end of the skewer against the fold and the other end showing at the bottom, like a lollipop.
  4. Tape the template together, with a picture showing on either side.
  5. Hold the stick between your hands and twist it slowly. The template will flip from one picture to the other. Speed up the twisting. What do you notice?

Try this with other pictures! What else would you like to put in a cage?

What's happening?

You've made a thaumatrope! When you twist the skewer in your hands, the two images seem to merge. This is a type of optical illusion.

When you look at images, your brain remembers them for a fraction of a second after the image has disappeared. This is called "persistence of vision".

If you see more than 10 images per second, your brain puts them together as a series of moving images.

Films use the same trick. In films, there are 24 still images (frames) per second. Your brain puts all those images together as a series of moving images.

Curriculum information