One of the most entertaining and educational polymer experiments around is the making of “Slime.” Everyone loves to make slime! There are two types of slime you can make: guar gum or polyvinyl alcohol slime. Both types of slime use sodium borate as the second ingredient. Guar gum slime is the easiest and fastest to prepare and is an excellent choice for elementary and junior high school teachers. However, the consistency of this slime is not quite as good as the polyvinyl alcohol slime and may be clumpy if the guar gum powder is added too quickly to the water. Polyvinyl alcohol slime requires a bit more preparation time and may be touchy to make, especially if you are starting with the powders rather than the 4% solutions. However, it makes fantastic “slimey” slime. Teachers with a magnetic stirrer/hot plate may want to make polyvinyl alcohol slime. With either option you'll enjoy making slime with your students!