Steve Spangler uses Gak to talk about Glaciers. Follow Steve and his team as they head to Alaska at www.ScienceAtSea.com Is it a solid? Is it a liquid? Just what is this slimy, stringy, rubbery stuff? This variation on slime will probably remind you of a similar substance found in many toy stores. This is the most popular version of "slime" among teachers because it's so easy to make and serves as a great visual tool for introducing students to the properties of polymers.