Pencils Through a Bag

When pencils are pushed through a water-filled plastic bag, no water leaks out.

1. Fill a resealable plastic bag about two-thirds full of water and seal it tightly.
2. Hold the bag over a sink, bucket, or outdoors to avoid spills.
3. Carefully push a sharpened pencil straight through one side of the bag and out the other side.
4. Try with additional pencils to see how many can be pushed through without leaking.

The Pencils Through a Bag Experiment - We Are Teachers:

Science Behind A Pencil Thru a Bag Full of Water (No Spills!) - SD Lab Rats:

📄 Poke but don't Soak - ACS: https://www.acs.org/education/whatischemistry/adventures-in-chemistry/experiments/poke-dont-soak.html

• Use colored water in the bag to make leaks easier to see.
• Experiment with other sharp objects (toothpicks, knitting needles) to compare results.
• Measure how many pencils can be pushed through before the bag eventually leaks.

• Adult supervision required - pencils and skewers are sharp.
• Perform over a bucket, sink, or outdoors to contain spills.

• Why doesn’t water leak out of the bag even when pencils poke through it?
• What property of polymers allows the bag and balloon to stretch and reseal around the objects?
• How is the material of the bag different from stiff materials like glass or wood?
• Where in everyday life do we rely on flexible, sealing materials like this?