The Magic Science Bag


Doing science with your kids can be a bit like performing magic tricks. I certainly got my kids attention when we attempted this experiment.

What you need: one gallon sized Ziploc bag and a dozen sharp pencils

How to do it:

  • Fill the Ziploc bag about 3/4 full of water
  • Close the bag and poke one sharp pencil at a time through the bag
  • Observe how the plastic bag seals around the pencil
  • See how many pencils you can poke through without making the bag leak!

Check this out

Simple. Easy. Science. Magic!

What is happening:

Ziploc bags are made from a polymer call polyethylene. Polymers consist of many molecules that are stuck together in long repeating chains. Some polymers you  might recognize include rubber, Teflon, polyester, and Kevlar! Polymers can be stretchy, hard, and even bulletproof!

This experiment demonstrates how polyethylene can be broken and will come back together to form a seal around the pencil. Science magic at it’s finest!

There are two great things that happen after you do this experiment.

#1. What’s more fun than poking pencils through a bag of water? Taking out the pencils poked through a bag of water. Try it, you’ll like it.

#2. After this experiment Allie’s skipped away looking for her own experiment to do. That is because when you introduce a little bit of science into your kids life they will “magically” look for more science to do.

How many pencils can you poke in a gallon size bag of water before it leaks? We tried 10 but I bet you can do more!

And for extra credit, how many times do I say “fun” in the video? Leave the answer below in the comments!

Categories: 5 minute experiments, how to videos, STEM | Tags: , , , , |


  • Morgan Gist MacDonald | March 2, 2016 | Reply

    Fantastic video, Tracy!!! You make science look so easy and fun, I love it 🙂

    • Tracy | March 2, 2016 | Reply

      Thanks Morgan! I wasn’t so sure I was going to keep everything dry! I’m glad polymers liked me that day!

  • Agnes Steelhammer | March 4, 2016 | Reply

    That was fun. Even I thought the bag would leak.

    • Tracy | March 4, 2016 | Reply

      Me too! Good ol’ polymers!

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