Re: How can kindergarteners make slime at home and explanations

Dear Kindergarten Teacher,

First here are some internet links that tell how to make slime with safe and readily available materials. In the Mad Scientist Archives there is a superb procedure that uses a white glue, such as Elmer’s Glue, food coloring, and borax, which you can pick up in the laundry goods section of a supermarket. The web page is in the MadSci Network's Edible/Inedible Experiments Archive. You’ll find all the necessary information there excellently put together. Another slime can be made from just coloring, cornstarch, and water (Family Internet). The ingredients of another recipe are unflavored gelatin, detergent, vegetable oil, and coloring: US Department of Education.

Your six year old son's hypothesis is actually pretty good. The key is to pick the right solids andliquids to mix. Salt and water won't do it because the salt dissolves as very small charged atoms called ions. These are too small to change the water. Sand and water won't work because the sand will just get wet and settle. If, however, the solid is the clay mineral bentonite the particles swell up large enough to become soft, and squishy. Mixtures of bentonite and water can be very slimy. Elmer's glue contains the polymer polyvinyl alcohol (PVA). These large polymer molecules react with the small borax ions to form a large squishy network full of water.

Thanks for the interesting question. A real explanation of slimy stuff would require examination of its viscosity, elasticity, and adhesiveness.