Shrink a crisp packet

Shrink a crisp packet

From big to small - shrink it!

Check out our new astronomy project...

Cosmic Comics Banner

Click here to find out more


Have you ever eaten a packet of crisps and wondered what to do with the wrapper?

Try this!

What you need:

  • Oven
  • Plastic (not foil) crisp packet - try a supermarket own brand, Chipsticks or Space Raiders
  • Water
  • Washing up liquid
  • Paper towel / dish cloth
  • Baking tray
  • Foil
  • Oven glove

How to:

Ask an adult for help using an oven.

  1. Preheat the oven to 250 degrees Celsius.
  2. Eat your crisps.
  3. Clean your crisp packet using water and washing up liquid.
  4. Dry the crisp packet.
  5. Cover the bottom of the baking tray with foil.
  6. Put the crisp packet on the foil and put the baking tray in the oven.
  7. Leave the crisp packet for two to three minutes.
  8. Ask an adult to take the baking tray out of the oven - make sure they use an oven glove!

What has happened to the crisp packet?

Crisp packet shrunk

Shrunken crisp packet

You could make your tiny crisp packet into a keyring! Punch a hole in the corner of the crisp packet and add it to a key chain.

What's happening?

This experiment will only work with plastic crisp packets, not foil ones. Plastic crisp packets are made from long chains of molecules called 'polymers'. In crisp packets, these polymer chains are stretched out straight.

When you heat up the crisp packet, the polymer chains start to get more energy. This makes the polymer chains vibrate and start curling up. The wrapper seems to shrink because all the polymer chains have curled up over each other!

Curriculum information

  • Summary


    Curriculum key wordsOther web links
    • 5
    Science Curriculum Links
    National CurriculumCurriculum for excellenceNorthern Ireland Curriculum