Oobleck is made with cornstarch and water, creating a fascinating mixture that can act like either a liquid or a solid. In this guide, we’ll explain how to make oobleck. The recipe is quick, simple, and enjoyable for children to prepare. Compared with slime, it requires far fewer ingredients and offers just as much hands-on fun!
You only need cornstarch and water to prepare oobleck, so there’s a good chance both ingredients are already in your kitchen! Food coloring is optional. We used green coloring to turn our mixture into a spooky pretend Witch’s brew for Halloween. Leave it white or use any shade you like.
Kids will love feeling, squeezing, and exploring this easy homemade mixture! If slime is on your activity list too, you can find all of our slime recipes here.
What Is Oobleck?
Oobleck is a non-Newtonian fluid, which means it is not truly a liquid or a solid. Depending on how you handle it, it may appear to be either one, but it does not act like a typical solid or liquid. Making oobleck is a fun science experiment that shows how pressure can change the behavior of some materials. A similar idea can be seen with water and temperature: cold conditions turn water into ice, while heat melts the ice back into liquid water.
Here’s what happens when pressure is applied to oobleck: Quickly push a spoon into the mixture, and the cornstarch particles become compressed, causing the oobleck’s viscosity to increase. It feels hard, and you may even be able to roll it into a ball with your hands. Stop pressing or gently move the spoon downward, and the mixture starts acting like water. Slow movements give the cornstarch particles time to move around one another.
For a story connection, read the Dr Seuss classic, Bartholomew and the Oobleck.
Oobleck Ingredients
Here are the ingredients you’ll need for this oobleck recipe:
Note: Cornstarch may also be labeled cornflour. Make sure you choose white cornflour.
How Long Does Oobleck Last?
Oobleck can be used for one day. After that, it starts to spoil.
When you’re ready to dispose of it, we recommend leaving the oobleck to dry overnight. The next day, use a spoon to break it into pieces and place them in your green bin. If you need to wash it away, dilute it with a generous amount of hot water beforehand.
Watch the Video Tutorial!
How to Make Oobleck: Step-by-Step Instructions
Use the following steps to prepare your oobleck:
1. Place 2 cups of cornstarch and 1 cup of water in a bowl.
Combine the two ingredients, stirring until the mixture forms oobleck.
Tip: For colored oobleck, stir the food coloring into the water before adding the water to the cornstarch.
Halloween Activity Suggestion: Prepare several batches of this recipe until your cauldron is full to make a Witch’s brew oobleck. This 14 inch cauldron is an excellent choice for the activity.
2. If the oobleck is too runny and will not hold together when lifted from the bowl, mix in more cornstarch.
If it refuses to move like a liquid, add a little water and stir again. Keep adjusting the mixture until it reaches the consistency shown in the video above.
Activity Suggestions:
- Quickly tap the top of the oobleck with a potato masher or spoon. The utensil should bounce back, making the mixture appear solid. As mentioned above, pressure forces the cornstarch particles closer together and raises the oobleck’s viscosity. Then slowly press the spoon into the mixture. Because the particles can shift out of the way, the spoon will gradually sink.
- Scoop the oobleck into your hands and roll it into a ball. Once you stop squeezing, watch it melt and run between your fingers!
- Make a Halloween version! Add small spiders, plastic eyes, and about 10 batches of oobleck to the cauldron, adjusting the amount to suit its size. Use green or purple coloring to create a Witch’s brew appearance!
Children will enjoy dipping their hands into the witch’s brew and looking for Halloween treasures while learning about the science behind the mixture!
Your children are sure to enjoy this easy science experiment! It makes a great Halloween activity and is also perfect for keeping kids busy on a rainy afternoon. For more hands-on science fun, be sure to check out all of our slime recipes!
More Science for Kids
- Fluffy slime is another exciting experiment to make! Its consistency is different from regular slime, which makes it particularly fun to handle and play with.