Science Spotlight


If you look closely at a brick house you’ll notice something very peculiar. All the bricks are layered in a specific pattern. This helps make the house strong! In science we can see something similar with polymers. Polymers are very big molecules that are made up of a bunch of smaller molecules layered together in a repeating pattern. The smaller molecules are called monomers. You can think of monomers like paper clips that link together to form a chain, and the chain is the polymer! Polymers can both be naturally occurring and created in a lab by scientists. Polymers that occur naturally include DNA. DNA is what makes us who we are and contains all of our genetic information. It is made up of long repeating patterns in the shape of a double helix. Polymers that are created by scientists include most plastics. Polymers are what cause plastic to be stretchy. Do you think you can push pencils through a plastic bag of water without making it leak? Try this experiment to find out!

Materials: Plastic ziploc bag, water, several sharp pencils.

Directions: Fill the plastic bag about ¾ full with water. Take the sharp pencils and push them through the bag! What happens?

How It Works: When the pencil breaks through the bag, it is inserting itself between the chain of molecules that make up the polymer. The chain of molecules stretches, but doesn’t break. The chain then seals around the pencil and becomes leak proof – no water spills out!

Want more? Research it! Try this experiment again with different sized pencils and different types of plastic bags. Does it always work the same way? Why or why not?