Teacher Handout
How it Works:
(Teacher/Parent
Supervision Required)
Why it Works:
IT’S NOT MAGIC,
IT’S POLYMERS
Plastic bags are made out of
polymers, which are long chains of
individual molecules, called
monomers. When you puncture the
bag with a sharpened pencil, you
are separating polymer chains
without breaking them. The
polymers than squeeze in tight
around the surface of the pencil,
which prevents the bag from
leaking.
Resource Citation:
http://www.stevespanglerscience.com/lab/experim
ents/leak-proof-bag/
ALL IMAGES ARE FROM GOOGLE
Materials: Plastic bag, Sharp colored pencils,
paper towels, and a cup of water.
Procedure:
Step 1: Fill the bag with one cup of water.
Step 2: One student should slowly push a
sharpened pencil through one side of the bag.
Step 3: Keep pushing the pencil until it breaks
through to the other side of the bag.
Step 4: Continue pushing sharpened pencils
through the bag and see how many you can do!
Safety Concerns: Do not push the pencil all the
way into the bag. Once the eraser or end point
of the pencil goes through the first opening, the
bag will start to leak. You need to be gentle and
push the pencils slowly through the bag, which
will help prevent leaks.
The Magic
Leak-Proof Bag
By: Michelle DeLano
Description of use in the
classroom:
The activity meets the Science SOL
3.1. It can be used to help students
understand how to make predictions
and the student will practice making
scientific observations.