A few years ago, homemade slime (sometimes known as Gak or goop) became all the rage, with all-in-one kits showing up on store shelves and YouTube tutorials saturating iPads everywhere. Perhaps this explosion was the next logical step in a worldwide push to get kids excited about science, technology, engineering and math (STEM) careers. Or maybe the activity took a cue from fidget spinners and snowballed into a fad.
Either way, making slime is an epic way to introduce them to the concept of non-Newtonian liquids, which act as solids sometimes and liquids in other situations. Long strings of molecules called polymers are ultra-important to slime recipes because they act as liquids until other chemicals are introduced, giving slime its somewhere-between-a-liquid-and-a-solid makeup, thus turning it into a non-Newtonian liquid.
A typical slime recipe involves school glue and borax (and some food coloring). School glue has an ingredient called polyvinyl acetate, a liquid polymer. Borax, often used as a laundry additive, is another name for the chemical sodium tetraborate. When the two ingredients are combined, the sodium tetraborate causes the polyvinyl acetate molecules in the glue to stick together and create one big putty-like polymer (a process called cross-linking).
Sure, you can purchase ready-made slime in a can, but where's the fun in that? We've got some recipes for super-satisfying slime concoctions below.