- Make sure your pencils are all sharpened.
- Add water to your zip-lock plastic bag and close it tightly.
- Stick your pencils through the bag and see what happens! (Tip: Try this outside or over a bucket in case of an accident.)
- Younger Children:
- Have an adult poke the pencils through the bag, and task your child with pulling them out.
- Keep your plastic bag over a bucket and play in the water that comes out of the pencil holes.
- Older Children:
- Test to see if this experiment works with liquids other than water.
- Grab some sharp colored pencils and colored sharpies. Draw different colored circles on the bag with the sharpies and turn this experiment into a color-matching poke game!
- Try this experiment with dull pencils. What happens?
Why Does This Happen?
Plastic bags are made up of long chains of molecules called polymers.
Polymers are what makes a plastic bag stretchy. When the sharpened pencils pierce through the bag, these long chains of molecules seal around the pencils within seconds, thereby preventing a leak.
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