Rubber Molecule Paper Model Puzzle by Bryce Hixson
Hold up a single sheet of paper and ask the kids to cut a hole in the paper large enough for you to walk through . . . without having to duck. If you are 6'8", like me, this is an even more interesting challenge. Introduces physical changes and polymers. Also provides ideas about how rubber molecules are linked and have the elastic quality that allows them to be stretched and wrapped so easily.