This activity explores the creation of colored slime by mixing three liquids together: polyvinyl alcohol, borax, and food colorings. By mixing polyvinyl alcohol and borax together, a change in the physical properties of polyvinyl alcohol occurs in which it turns from a liquid to a gel (highly viscous liquid). Observers will experience a liquid becoming increasingly thick as they stir the 3 liquids together. From this activity, kids will learn how and why changes in physical properties of a substance occur.