Magical Plastic Bag Experiment

What happens when you poke a sharp pencil through a bag of water?

Materials

• Zip up bag

• Water

• Sharpened pencils

Directions

1. Fill the bag about halfway with water. Seal it.

2.  Hold the bag over a sink

3. Poke pencils straight through it (so the pencil pierces both sides). Repeat a few times.

4. Observe that the water isn’t leaking

5. When you’re finished, remove pencils over a sink.

Why it Works
Plastic bags are made out of polymers, chains of molecules that are flexible and give the bag its stretchiness. When the sharp pencil pokes through the bag, the stretchy plastic hugs around the pencil, creating a watertight seal around the pencil…and the bag doesn’t leak.

Adapted from Tinker Lab