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Easy Science Experiment: Pencil Through a Bag

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Science is best learned (and more fun) when done through easy, exciting science experiments.

Read on to learn how to do this easy science experiment that involves putting a pencil through a plastic bag full of water!

STEM Experiment Pencil Through Bag Magic Trick - MamaTeaches

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The Pencil Through a Bag experiment is super easy and quick to do.

In a homeschool setting or a traditional school classroom, this would be a wonderful way to step away from the regular workspace.

STEM activities make for valuable lessons for kids of all ages.

This particular science experiment is good for Elementary to Middle school-aged children.


Before you get started on this experiment, gather the materials below.

To ensure everyone can try this for themselves, be sure to multiply the number of each material by the number of students or kids you have to do the experiment.

  • A Plastic zippered top gallon-size bag
  • At least 1 very sharp pencil
  • Water
  • Paper Towels (just in case)
Easy Science Experiment - Pencil Through Bag STEM Experiment for Kids -


Because this experiment uses water and sharp objects, it is probably best done outside.

If you’d like to try this at home, but don’t have a great outdoor space to try it out, do the experiment over your kitchen sink.

  1. Now, fill your plastic bag up about 3/4 of the way with water. This step should be done with two people to prevent spillage! Zip the bag up tightly.
  2. Being sure that it is closed tight, hold the bag up and out in front of you. Poke the pencil through one side of the bag and out through the other side. *Disclaimer: Stabbing the bag too quickly will cause it to rupture and can definitely get water in places you don’t want!
  3. Repeat step two with as many pencils as you want.

Watch us try the experiment!


Plastic zippered top bags are made up of polymer.

A polymer is a substance that consists of chains of molecular units.

These chains are so tightly bonded that when the pencil is pushed through the bag, the molecule lines will bend around the pencil to create a seal.

This is why the water doesn’t leak out!

This science lesson can be made more complicated if you have older kids by discussing other chemical bonds and how those bonds can be broken.

The very basic take away is that some things that we use in our daily lives, like the plastic bag, are made of much stronger molecular bonds than we may have realized.

STEM EXPERIMENT - Pencil Through a Bag Science Experiment -

How many pencils can you stick through your tightly bonded polymer bag?!

Take a picture and tag us on Instagram @MamaTeaches.

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