Our 6th grade STEM elective students in Mrs. Jillian Griffith's class got a chance to learn about polymers and the effect they have on materials with a fun STEM challenge. They took sandwich bags filled with water and poked sharpened pencils all the way through them to see if the bag would leak or not. To their surprise it didn't! One group was able to poke 50 pencils in their bag.
If you are wondering how this works with no water leaking out it is all about the polymers. The plastic bag is made up of polymers (long strands/chains of molecules). When the sharpened pencil pushes through the plastic bag it is actually pushing through the polymer strand/chain. The strands are pushed aside by the pointy pencil being inserted through the bag but quickly reseal themselves around the pencil preventing the water from leaking out of the bag.
