Liquid in a Bag Experiment

We had great fun carrying out this experiment. Here’s the science behind it:

The plastic bag is made of a polymer, a stretchy material made of long chains of molecules. When you push the pencil through, the sharp tip slides between the polymer chains without breaking them. The plastic stretches and forms a tight seal around the pencil, stopping the water from leaking out. This happens because the polymer chains are flexible and can move around the pencil, creating a waterproof barrier. It’s a great example of how polymers are both strong and stretchy!