free activities
Homemade Oobleck

Combine a great book with great fun! As a read aloud or a read alone, Dr Suess puts the fun into summer reading for kids. The name Oobleck comes from the 1949 children’s book, Bartholomew and the Oobleck, by Dr. Seuss. In the story a sticky liquid falls from the sky as a result of the king becoming bored with normal weather.  Recreate the Seussian town that is overcome with gooey, green, schlumping piles of Oobleck – build a lego village and let the Ooblek rain down!

What you will need:

  • cornstarch
  • water
  • bowl
  • green food dye

What you will do:

  1. Mix two scoops of cornstarch with one scoop of water.
  2. Add a couple drops of green food dye.
  3. Mix by hand.
  4. Add water or cornstarch until ooblek is solid when squeezed, but liquid when released.
  5. Have fun playing! Try experimenting with the ooblek.
  6. If you let it settle, then smack it, is it solid or liquid?

Why is this happening?

Oobleck is a suspension of cornstarch and water that can behave like a solid or a liquid depending on how much pressure you apply. Materials that behave this way are classified as non-Newtonian liquids because their flow properties are not described by a constant viscosity (or flow rate). Molasses has high viscosity while water has low viscosity. Ooblek’s viscosity changes depending on the pressure put on it.

One thing to keep in mind is that Oobleck is a suspension, not a solution. The cornstarch does not dissolve in the water like salt or sugar would. Instead, the tiny starch particles are suspended in the liquid. If you let it sit long enough in a glass, the cornstarch will settle to the bottom leaving a layer of clear water on the top.

Looking for more ooey gooey slimy fun? Try making Flubber!