Inside: This Magic Peppermint Oobleck is made without cornstarch. It’s my favorite kind of science activity: low effort, big reward! Plus, the science behind oobleck, and fun suggestions for what to do with it.
I was going to call this post “Coronavirus Oobleck,” but I thought that name might confuse my readers.
You see, over Thanksgiving, my whole family came down with coronavirus. At first, we didn’t realize it was coronavirus. It felt just like a regular cold with a bit of congestion and a touch of sinus headache.
While we were homebound, I kept my youngest ones busy with Jell-O playdough, candy slime (all that Halloween candy had to be put to good use!), and peppermint oobleck.
It was while making the peppermint oobleck that I realized that what I thought was just a regular cold was actually the coronavirus.
I couldn’t smell peppermint!
I kept adding more and then stuck my nose right in.
So I put the bottle down and started running around the house, smelling everything.
A slice of lemon on a plate.
My dog (and we all know how stinky their breath is… pee-yew).
My favorite perfume (Poison by Christian Dior).
Zilch. Na-da. Huge nothing.
I’m happy to report that our sickness never progressed beyond the regular-cold stage, and we already run a 5K race. But I think the name stuck. In my family, we will always refer to peppermint oobleck as coronavirus oobleck.
The Science of Oobleck
You don’t have to wait till you suspect the coronavirus to make this recipe.
While exploring oobleck, your kids will learn:
- chemistry (the properties of non-Newtonian liquids)
- cause and effect (applying pressure to the oobleck increases its viscosity (thickness), relaxing pressure makes it flow like liquid)
- science concepts (the states of matter: liquids and solids, plus pressure and viscosity)
- comparison (one-moment the oobleck is solid, the next it’s a liquid!),
- experimenting (pouring, poking, pinching, and scraping)
- the relationship between science and the real world (how understanding the properties of oobleck can help food scientists make better peanut butter, for example).
Whether you call it oobleck, non-Newtonian liquid, magic goop, the Seussian goo, or any other name, you will agree it’s pretty exciting. (Even for me, and I’m an adult). Oobleck is a magic substance, both a liquid and a solid.
How can that be?
To understand the properties of non-Newtonian liquid, you need to go back to your chemistry class. A liquid is a substance that flows freely because it consists of molecules that are connected by intermolecular bonds that can slide past each other. A solid has a rigid shape because the molecules are tightly connected via chemical bonds.
Oobleck, on the other hand, is something that is both. It can act as a liquid at rest, and it can act like a solid when you put it under pressure.
Oobleck is made up of molecules called polymers arranged in long chains of repeated units. The molecules can be stretched out or stuck together depending on the conditions that act upon them.
When you hit or squeeze an oobleck, the physical pressure forces the molecules to stick together, turning it into a solid.
But as soon as you let the molecules “relax” (meaning that there is no force acting on them), the polymers stretch out, and voila: it’s a liquid flowing between your fingers … and uh-oh all over mom’s favorite ….. [insert your favorite here].
Don’t worry, oobleck is super easy to clean up. Just wipe it off the hard surfaces. If it gets on a carpet, let it dry, and then vacuum it up. If it gets on your clothes, use the hottest temperature your fabric allows, and wash it off.
When you are done playing with your oobleck, scrape it into the garbage can. Don’t wash it down the drain.
I’ve written about the properties of oobleck and other non-Newtonian fluids in a Peanut Butter post. Head on over there if you would like more information.
A Note about the Ingredients
If you’ve done oobleck activities before, you probably used cornstarch because that’s the way it was traditionally done in the past. Now that many people avoid corn products, other foods can help us achieve the same results.
- I’m a huge fan of arrowroot powder and tapioca flour. I add them to soups, sauces, pancakes, and cookies as a thickener. So, we experimented (successfully!) with these alternatives to make our oobleck.
- Peppermints are not an integral part of the activity. We added candy because we had them from trick-or-treating, and that was as good use for them as any. Your candy might create enough pepperminty aroma to skip the next ingredient.
- Peppermint oil! Yum! As I said, depending on your brand of peppermint candy, you might feel that your activity is already as pepperminty as it needs to be. However, we believe in the power of peppermint to spread magic, happiness, and cheer this time of the year all over the world. Kidding. We just like it a lot 🙂
Peppermint Oobleck Recipe
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- 1 ¼ cup potato starch, tapioca flour, or arrowroot powder
- 1 cup water
- A few drops of Peppermint oil (I used cooking grade because that’s what we had on hand)
- About a dozen Peppermints
- Butter or plastic knife (for cutting oobleck)
- Dolls or LEGO figurines (for “Help! I’m sinking!” sort of play)
- Plastic animals
- Magnifying glass
Note: Scrape it into the garbage bag once you are done playing with oobleck. Don’t wash it down the drain.
Scroll down for details or watch our video! You can get the sense of excitement this project created from my daughter’s exclamations:)
What to do
- Measure out 1 and 1/4 cup of starch and add it to your bowl (we used tapioca today). Stir in 1/2 cup of water and mix it.
2. Add a few drops of peppermint oil and stir. We didn’t bother to measure because Can you have too much peppermint? I don’t think so!
However, note that we are using cooking grade peppermint, which is quite mild. If you are using peppermint essential oil, make sure to use very little as undiluted essential oils might be harsh for your little ones.
As you stir the oobleck mixture, watch for consistency. Each starch is a little bit different, so in some cases, you might need to adjust the volumes. If your mixture doesn’t flow, add more water. If the oobleck is too loose, add more starch. Only add a spoon or two at a time.
Now let’s move on to fun things to do with oobleck.
Fun things to do with Magic Peppermint Oobleck
- Dip your fingers into the oobleck slowly and gently.
How does it feel? Solid or liquid?
Now lift your hands up.
Oobleck should be oozing out of your fingers.
- Punch it hard.
Did you notice a difference? Does it feel like a solid or a liquid? Like a solid because pressure makes oobleck hard.
- Squeeze it in your fist or make a ball with it. Now release the pressure.
What’s happening? Did you notice that applying pressure makes it harder?
- Pour it into another bowl.
Does it flow or act like a solid?
- Try to get all the peppermints out.
The harder you try, the harder it is because it’s the pressure that makes oobleck hard.
- Can you cut it with a plastic or butter knife?
- Grab a magnifying glass.
Oh-oh, what’s happening to the peppermints? They are losing their stripes and shrinking in size.
- Use tweezers to pull a few peppermints out and examine them on all sides.
Do they look different from each other and from how they looked at the start of the experiment?
- Grab a doll (or LEGO character) and make it jump on the surface of the oobleck.
Does it feel hard?
Yes, it does because tapping forces the starch particles together.
Now gently rest your doll on the surface and see what happens. It’s sinking, isn’t it? Why? Because the starch particles are slowly sliding past each other and moving out of the way.
10. Add some sparkle! If your kids are still not certain that oobleck is magical, a bit of sparkle is a sure way to convince them.
Note: When you’re done, do not put oobleck in a sink. Simply throw it in a trash bag.
Do you want to extend the fun? Try our Peanut Butter Experiment!