Holey Bag

A bit of science magic – why doesn’t a holey bag leak?

What you need:

• zip lock bag
• pencils
• water
• a dish to catch any accidental spills

What to do:

1. Put some water in a zip lock bag and close it tightly.
2. Hold the bag above a dish.
3. Gently push a pencil through the bag, where there is water. You might need to twist the pencil to get it through.
4. The bag won’t leak.
5. Put as many pencils in as you like.

What happens:

Plastic bags are made of long chains of molecules, called polymers. These polymers stretch as the pencil is pushed through, but once the bag breaks, they shrink around the pencil, so you don’t get any leaks, at least until you remove the pencils!

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