Leak Proof Bag

Can you poke a hole in a bag full of water without losing even one drop? Once you learn the science behind this leak-proof bag experiment, you’ll be ready to poke holes in a bag full of water while holding it over somebody’s head!

It’s the perfect compliment to our 30 Science Experiments you can find in our shop!

Getting Ready

Since this science activity involved water, we decided to do it outside, but it would have also been perfect for bath time.

Before heading out the door, we gathered a few simple supplies to perform our leak proof bag trick:

• Zipper storage bag
• Water
• Several sharpened pencils

We filled the zipper storage bag about 2/3 full of water. After squishing out the air, we made sure the zipper was sealed tight.

I asked my kids what they thought would happen if we stabbed a pencil through the bag. I always love to have them make a hypothesis and then see if it really happens. Sometimes the results can be surprising!

Using the sharp end of one pencil, I quickly pushed it through the bag. It went in one side and out the other – without spilling a drop!

To make it even more fun, I held the bag of water over my son’s head while I pushed more pencils through it. He was so scared he was going to get a shower at the park!

Once my kids saw that the bag wasn’t going to explode all over them, they were courageous enough to push some pencils through themselves. We added quite a few! We even squished the water gently around the bag and turned it upside down without spilling a single drop of water.

The Science Behind It

Plastic bags are made of a polymer called low-density polyethylene. Polymers are long chains of molecules. The tip of the pencil squeezes between the chains without breaking them but the chains’ flexible property helps to form a temporary seal against the edge of the pencil. This enables a pencil to pierce the bag without losing even one drop of water!

More Science

Want even more science kids will love?  Head over to our shop and snag our 30 Science Experiments – complete with a no prep journal to record results!