Why make a Pumpkin oobleck? Because we love pumpkins! I have been so excited for all the awesome fall sensory activities we have tried this season. This non-Newtonian fluid is super fun when you add it to a pumpkin! Find new ways to learn and play with pumpkins this fall season.


Pumpkin oobleck cornstarch recipe with ral pumpkin to explore physics, states of matter, and non-newtonian fluids

What Is Oobleck?

Oobleck is a fun mixture to play with, which is made from cornstarch and water.   It’s a bit messy too!

It is a great example of a mixture!  A mixture is a material made up of two or more substances combined together to form a new material and that can be separated again.

Do you think the oobleck mixture could be separated into cornflour and water again?  How?

Try leaving a tray of oobleck out for a few days.  What happens to the oobleck?  Where do you think the water has gone?

Oobleck Is A Non-Newtonian Fluid

This oobleck activity is also a great way to explore the properties of liquids and solids, know as the states of matter.   Here we are combining a liquid and a solid, but the mixture doesn’t become one or the other.  A solid has its own shape whereas a liquid will take the shape of the container it is put into.  Oobleck is a bit of both!

That’s why oobleck is called a non-Newtonian fluid.  This means it is neither a liquid nor a solid but has properties of both!  You can pick up a clump of the substance like a solid and then watch it ooze back into the bowl like a liquid.  Touch the surface lightly and it will feel firm and solid. If you apply more pressure,  your fingers will sink into it like a liquid.

Is oobleck a solid? Or is oobleck a liquid?

Did you know that cornstarch is a polymer? Polymers have long chains that make them up (like the glue used in slime). When these chains get all tangled up with one another, they create more of a solid!

Make sure to also check out our Pumpkin Volcano (with video)!pumpkin oobleck science sensory play spilling out of pumpkin

Pumpkin Oobleck 

Here’s how to make this super simple 3 ingredient hands-on science play with real pumpkins! I love checking out my kitchen pantry for supplies for science experiments.


  • cornstarch
  • water
  • pumpkin (we used half of a 3-pound sugar pumpkin from the grocery store)
  • bowl and plate or cookie sheet and spoons

We made an awesome, simple, one bowl, grain-free pumpkin bread with the other half! Click here for the recipe

How To Make Pumpkin Oobleck

As I said above, we only used half a pumpkin which was perfect for our needs. If you have a few kids or a class, use the whole thing! However, we did bake the other half and made a delicious fall treat with it!

This mixture is for 1/2 a pumpkin. You might want to mix the oobleck a half at a time of you are using the whole pumpkin. It’s definitely a recipe you need to tweak to your liking and sensory needs.

STEP 1. Cut the pumpkin in half and loosen the guts and seeds (awesome time to discuss pumpkin parts too!) Set aside a few seeds to top the pumpkin afterward.

STEP 2. Measure 1 cup of cornstarch and pour into the pumpkin.

STEP 3. Add about a half cup of water to the pumpkin.

STEP 4. Mix well with hands! If the mixture feels too runny add a bit mmore cornstarch. Too dry? Add a bit more water. Just make sure to add very small amounts at a time!

STEP 5. Place the pumpkin on a cookie sheet or in a shallow tub for easy play.

Mixing Note: If the mixture is too runny, add more cornstarch and vice versa. You should be able to pick it up like a solid and have it begin to ooze as a liquid. That’s oobleck in a nutshell! Also note, you may need to adjust for the number of pumpkin guts in your pumpkin and the size of the pumpkin!

Sensory Note: This definitely can get oozy and gooey and provide quite a sensory punch. It’s not for everyone. My sone enjoys using spoons but doesn’t necessarily care to get it all over his hands, so I don’t push it. He does enjoy oobleck because if you poke it with your finger it feels firm and smooth with little residue.

Conduct An Oobleck Experiment 

Want to experiment with viscosity?  Easy, change the ratio of water to cornstarch!  Viscosity is the physical property of fluids and how thick or thin they are, including how they flow.

  • What happens when you add more cornstarch?  Does the oobleck become thicker or thinner?
  • What happens when you add more water?  Does it flow faster or slower?

YOU MAY ALSO LIKE: Applesauce Oobleck and Halloween Oobleck

Can you make oobleck without cornstarch?

You could try making oobleck with flour, powder, or baking soda and compare the similarities and differences.

We tried an oobleck experiment of our own using just cornstarch and glue.  Find out what happened —> Oobleck Slime

Check Out More Fun Pumpkin Activities 


Click on the link or below for more fun pumpkin activities to try.

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