Program 22: Happy Birthday, Dr. Seuss – Let’s make oobleck!

In a happy birthday nod to Dr. Seuss, I thought it would be great fun to let my Science Explorers make some wacky and wonderful “oobleck” (given its name from Bartholomew and the Oobleck by Dr. Seuss).  The one and only other time I attempted this program was back in 2014. It was successful…until my scientists started modifying the recipe. And then we had a messy DISASTER on our hands that involved many hours of scrubbing the library floor to clean up. But I’m a little older and wiser, so I was pretty confident I knew how to modify the program to work out just fine…and it did!

Sadly, I don’t have any photos taken during the program itself because my hands were just as mucky and messy as anyone’s, but I can certainly describe what we did and how we did it 🙂 But first, the key to this project is learning what exactly a non-Newtonian liquid is.

Non-Newtonian Liquids

Our dear scientific friend Sir Isaac Newton first described the scientific properties of liquids.  Basically, Newton said that a liquid will remain at the same “viscosity” (or rate of flow, or thickness) regardless of the conditions. For example, let’s say you have one cup of water and you place it into a mug.  If you then pour that one cup of water into a skinny flower vase, what happens to the water? It adapts the shape of the new container. It is still one cup of water regardless of which container it is in.  Now, let’s say you had a Pokemon figurine, and you place that Pokemon into the mug. If you then move the Pokemon to the vase, what happens to the figurine?  That Pokemon figure, a solid, does NOT change it’s shape to adapt. It will always, inflexibly, stay the same shape and size.

The cool thing about non-Newtonian liquids is that they act like BOTH a liquid AND a solid under different conditions.  If you were to slowly press your hand into a container of a non-Newtonian liquid, it would slowly sink into the material as if it is a thick liquid (like quicksand). However, if you make a fist and quickly punch the surface of the non-Newtonian substance, it will now act like a solid.

The Oobleck Recipe

Materials:

  • 1 cup of water
  • 1 to 2 cups of corn starch
  • Mixing bowl and spoon (I gave my scientists each a plastic tupperware container, purchased from Ocean State Job Lot. They were able to just put a lid on the mixture and take it home at the end of the program)
  • Optional: Food coloring

The recipe is very straight forward. The trick is getting the ratio just right between the water and corn starch. When I did test batches with one cup of water and one cup of corn starch, I found that oobleck was too much like a liquid. I had to add about another 1/2 cup of corn starch to make my oobleck. You will likely need to abandon stirring with a spoon and just get your hands in there to combine towards the end. You can test this as you go along by swiftly poking the surface of the substance. If it behaves like a solid when you poke at it, then you’ve landed on the right mixture!  Food coloring is optional. It definitely makes it a little more fun, but I recommend wearing plastic gloves when adding any coloring (my fingers were a lovely shade of blue for several days because I was the one person allowed to add coloring to my scientists’ ooblecks).

Once you have your oobleck created, try just sinking your hand into the mixture. As you can see from the picture above in this post, the corn starch molecules will stay loose and separated if you slowly move your hand through the substance. If you punch or poke the surface, the corn starch molecules rapidly come together to form a solid barrier in the substance.  Try to make an oobleck ball in your hands by quickly rubbing together a fist-full of the substance. Once you stop rubbing the ball and keep your hand still, what happens to the oobleck? You should see that it returns to a liquid state and oozes back through your fingers.

  • TAKING IT FURTHER. Place your oobleck in a sealed container and leave it alone for a few days. What happens to the substance? Are there any other substances that behave like oobleck? [Hint: take a look at ketchup, toothpaste, shampoo, paint, and quicksand.]
  • Science-U of Penn State has a great online article on non-Newtonian liquids and was a source of some of my information. You can find that information HERE.