Pencil Trick

Pencil Trick



As your family gears up for back-to-school season, use some of your newly bought goods to test out a cool effect! With just three simple materials you can find at home,  you'll be surprised with what they can do!

How We Did It

Pencil Trick
Fill the plastic bag halfway with water.
Pencil Trick

Use one hand and hold the plastic bag at the top for stability.

Pencil Trick

Use a pencil to quickly pierce the bag and water!


What's going on?

Most plastic bags are made of polyethylene, a polymer that is durable, flexible, and shaped like long strands.  When the pencil is quickly pierced into the bag of water, the polyethylene molecules separate but don't break, forming a seal around the pencil. If the pencil is pierced into the bag before the water is put in, the water will leak!  


Try the experiment with a faceted pencil, a larger pencil, or a thicker plastic bag. What happens?

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where is "my projects"

posted by: Lucy on 8.21.2016

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