Would you believe me if I told you that we can poke holes in a bag full of water without water leaking out? Probably not, but that’s exactly what happens in this fun science experiment!
Prepare to be amazed, watch our demonstration video, then grab a plastic bag and a pencil to try it yourself! Printable instructions and a simple explanation of how the experiment works are included.
- Plastic Baggie
- Sharpened Pencils
Step 1 – Fill a plastic baggie a little more than 1/2 way full of water.
Step 2 – Seal the baggie. What do you think will happen if you poke the baggie with a pencil? Do you think it will create a hole in the baggie? If so, what do you think will happen next?
Step 3 – Quickly stab a sharpened pencil through the baggie. Make some observations about what happened. Did the pencil poke a hole in the bag? What happened to the water? Did you expect the water to leak out of the hole? Is the water leaking out? Write down your observations.
Step 4 – Try stabbing multiple pencils through the baggie. Are you surprised at what happened? Do you know the why the water didn’t leak out? Find out the answer in the how does this experiment work section below.
The magic of this experiment lies in polymers. Polymers are long chains of molecules that make up many items we use in our everyday lives – specifically plastic items. Zipper top plastic baggies (like the one used in our experiment), plastic grocery bags, plastic water, and soda bottles, and plastic food packaging are all made of polymers. Products made of polymers are flexible, lightweight, leak-proof, and low in cost to produce.
Think of polymers as long chains of beads. When you stab a pencil through the bag, the polymers move apart. This is the same as if you stuck a pencil between two chains of beads. Because polymers are flexible, when you stab a pencil through the bag, the polymers push back toward the pencil and form a temporary seal. This prevents the water from leaking out of the holes. If you remove the pencils from the bag, the holes will remain in the bag because you have permanently pushed the polymers aside, allowing water to leak out.
I hope you enjoyed the experiment. Here are some printable instructions: