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How to Make Oobleck | Fun Science Projects

a green slime splat.
Like Dr. Seuss' oobleck, non-Newtonian fluids get thicker as they are deformed, say by someone running across the fluid.
Credit: apartment, Shutterstock

Want to have fun with physics and even "walk on water"? Try making a mixture of cornstarch and water called oobleck. It makes a great science project or is just fun to play with.

Oobleck is a non-Newtonian fluid; it has properties of both liquids and solids. You can slowly dip your hand into it like a liquid, but if you squeeze the oobleck or punch it, it will feel solid. The name oobleck comes from the Dr. Seuss book, “Bartholomew and the Oobleck.” In the story, oobleck, a gooey green substance, fell from the sky and wreaked havoc in the kingdom.

Making oobleck is easy. Here's a recipe:

Oobleck ingredients

  • 1 part water
  • 1.5 to 2 parts cornstarch
  • Small amount of food coloring (optional)

Mix ingredients

  • Start with the water in a bowl (or wading pool!) and add the cornstarch a bit at a time.
  • Keep stirring until it has a gooey consistency. You may want to use your hands.
  • When the oobleck is just right, slowly add food coloring, if you want. This can be a challenge to get it mixed properly.
  • Play with it.

Here's a list of things to do:

  • Grab a handful and squeeze it. Let it ooze through your fingers.
  • Make a puddle and quickly drag your fingers through it.
  • Put it into a plastic container and shake it or quickly bump it against a table.
  • Jab at the oobleck and then slowly let your finger sink in.
  • Roll some oobleck into a ball. It becomes solid, but when you stop moving it, it will melt back into your hand.

Some science projects use oobleck. Experiments you can try include:

Put some oobleck on an old speaker and watch it dance:

Or, put it in a cookie sheet on top of a speaker:

Put a lot of it in a kiddie pool and walk across it:

Tips

  • Store in an air-tight container. Mix occasionally.
  • If you put in food coloring, you may notice a little bit of color left on your hands after washing. Don't worry. It should go away in a day or two.
  • Anything put into the slime can be washed with soap and water.
  • To dispose of the oobleck, mix it with a lot of hot water to make a very loose slurry. Pour a small amount into the drain while the hot water is running.
  • Oobleck when dried can be easily vacuumed.

Warnings

  • Don't drop on couch, deck, or sidewalk. It's hard to get off.
  • Oobleck isn't poisonous, but it tastes awful. Wash your hands after playing. Make sure children are supervised.
  • Wear old clothes, as oobleck tends to get messy.
  • Don't worry too much if it gets on something; it will come out with a little water.
  • Lay a couple newspapers on the floor so it doesn't get all over the floor or table.
  • Oobleck may solidify if it's not kept wet. If it hardens, just throw it away.
  • If oobleck is left out too long, it will dry out and turn back to cornstarch.

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