Slime

Materials

  • Mixing bowl

  • 1/2 Cup Washable PVA school glue (like Elmer's®)

  • 1/2 Cup Water

  • 1/2 tbsp Baking soda

  • 1 tbsp Contact lens solution (must contain both boric acid and sodium borate in ingredients)

  • Food coloring

Instructions

  • In the mixing bowl, thoroughly mix 1/2 C water, glue, and a few drops of food coloring.

  • Add baking soda and mix completely.

  • Add contact lens solution and stir vigorously until the mixture starts pulling away from the edges of the bowl.

  • Use your hands to knead the slime (fold it, squeeze it, and roll it) for 5–10 minutes until its texture stops changing.

Questions:

  • What did you observe while you were playing (pulling, touching, pouring, rolling, dropping etc.) with the slime?

  • If there was one ingredient you’d like to experiment with changing, then what would it be?

  • What is one thing about the environment around your slime you observed? (temperature, surrounding liquid, exposure to air for certain periods of time, etc.)

  • How do you think changing one of the ingredients or the environment would cause a change to your observations about the slime?

What is happening?

The glue has long flexible molecules in it called polymers. These polymer molecules slide past each other as a liquid.

Borax in water (contact solution) forms an ion called the borate ion. When the borax solution is added to the glue solution, the borate ions help link the long polymer molecules to each other so they cannot move and flow as easily.

When enough polymer molecules get hooked together in the right way, the glue solution changes from being very liquidy to a rubbery kind of stuff that we call slime!