Make a Leak-Proof Bag

Leak Proof (3)

This simple science experiment is sure to produce wide eyes and gasps in everyone from little kids to big grown-ups. Can you really pierce a hole in a bag filled with water, but not produce any leaks? Read on and find out!

First, gather a few sharp pencils, the sharper the better. We gave an extra honing to a few pencils, and set them aside.

Leak Proof (1)

Next, fill a large zip-top plastic bag half way with water, and seal tightly. We did the experiment over the sink just in case.

Leak Proof (2)

I stood Travis up on a stool and told him I could pierce the bag without causing a leak, only half believing it myself.

The pencils slid in surprisingly easily! Bam, three in, and not a drip in sight.

Leak Proof (5)

Travis loved it… and had even more fun pulling the pencils out and watching the fountain that erupts. We had to do the experiment three times it was so much fun.

Leak Proof (4)

Why does it work? It’s all thanks to the power of polymers, long chains of molecules that make up the plastic bag (in this case polyethylene). These molecules seal around the pencils once they are pushed through, preventing any leaks. Remember playing with silly putty as a kid? That’s another example of a polymer. So give your kids a tiny science lesson, and then simply have fun dazzling them. Bonus points if you do this over the floor instead of the sink!


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