Here at Science Sparks we love a bit of science magic and this leak proof bag is one of the best. My daughter used this for a school talent show when she was just 5 and the rest of the class loved it!
How to make a leak proof bag
Materials
Sharp pencils
Plastic sealable bag
Water
We made our bag Halloween themed by adding bugs and bouncy eyeballs, but you don’t need to do that.
Instructions
Half fill the bag with water and seal it carefully.
You need to be brave for the next part. Make sure your pencil is sharp and push through the bag, you don’t need to be especially fast, slowly and carefully works well.
Once you’re done, show your audience your leak proof bag.
Why does the leak proof bag work?
This trick works because the plastic bag forms a temporary seal against the edge of the pencil. If you were to take the pencils out the bag would leak.
Extension Tasks
Does a blunt pencil work as well?
How many pencils can you push through the bag?
Does the thickness of the pencil make a difference?
More Cool Science Tricks
Make an egg float, a lemon sink, defy gravity and more with our fun selection of cool science tricks.
Did you know you can step through an index card without breaking it?
Last Updated on March 31, 2022 by Emma Vanstone
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