Oobleck melts from a spoon into a bowl.

You may have made slime before, but have you made oobleck? This sticky yet solid combination of water and corn starch makes a quicksand-like compound that’s so fun to play with!

First, let’s learn a little about what makes oobleck so special. We have to start with matter! Matter makes up everything around you! Your shoes, your clothes, your dogs and cats, your eyes and hair, your whole body and the world around you is made of matter.

Matter exists in three states: liquid, solid, and gas. Liquids are fluid, which means you can pour them to move them around. You can easily put your hand or another object through liquid. Water, soda, and juice are all liquids: you can pour them into a cup, and you can swim in them, too! Solids are solid, though. You can’t necessarily put your hand through a solid. Wood, fabric, concrete, and plastic are all solid. Gases, like everything in our world, are made up of particles, but the particles in gases are far, far apart from each other, which means you can pass through them with ease, and some gases are even invisible. What are some gases you can think of? Hint: what is the name of the gas we humans have to breathe in to survive?

Now, matter is kind of complicated. Some matter can pass between all three states depending on the temperature. For example, water is a solid when it’s frozen, it’s a liquid when it’s at room temperature, and it’s a gas when it’s been heated enough that it evaporates. Cool, right? What other things can take all three states of matter? What about one of my favorite treats: ice cream! It comes from liquid milk but is frozen into a solid.

Not all matter follows these rules, though. That’s where oobleck comes in! Oobleck is non-Newtonian, which means it’s not normal and doesn’t follow the rules of matter like water or carbon. When you place oobleck under pressure, it behaves like a solid. But when you stop applying pressure, it behaves like a liquid. Want to see what I mean? Let’s make some!

Oobleck is just corn starch and water, so it’s easily washable! But food coloring stains clothing and carpet, so be careful!

You’re going to need some corn starch and some water to create your slimy oobleck, as well as a bowl, a spoon, and some measuring cups. You can add in some food coloring, too, if you want to make it look extra exciting!

First, measure 1 cup of corn starch into a bowl (or 2 cups for a bigger batch).

One cup of corn starch goes into your bowl.

Next, measure a half cup of water (or 1 cup for a large batch) into a cup. Now, you can color your water! I added a few drops of yellow dye to my water.

Add some food coloring to your half cup of water.

Once your water is colorful, it’s time to start mixing. Slowly mix the water into the bowl of corn starch, stirring the whole time. You should start feeling your oobleck getting sticky and slimy. That’s normal! Keep stirring until all of the corn starch is mixed in with the water.

Mix your water into your corn starch and stir, stir, stir!

If your mixed oobleck looks too flaky, add a tablespoon at a time extra of water. If you add to much, it will be too fluid. You can correct watery oobleck by adding another tablespoon full of corn starch. Your oobleck should look like liquid, but should feel kind of solid. It should melt off your spoon, but resist it if you quickly poke the mixture with your spoon. Like this!

Uhh, it kind of looks like melted cheese. More yellow dye might have helped brighten it!

Ok, time to start experimenting! See how oobleck has properties of liquid, but properties of a solid at the same time? Try tapping it with the spoon, a penny, or another small object, and watch how it resists being tapped like a solid. Now leave the object on the surface and watch it float to the bottom, as if it were liquid! Under pressure, oobleck reacts like a solid, but stop applying pressure and it seems like a liquid.

Run it through a strainer, try punching it with your fist, cut it with scissors, try to shape it with your hands, let your fingers sink to the bottom and then try to pull them out: it’s so weird! That’s why it’s identified as a non-Newtonian fluid. It doesn’t follow the normal rules of matter.

Check out the video below of a group of engineering students who put together a HUGE container of oobleck to experiment with. Wouldn’t you love to walk on oobleck? You’ll just need 2,000 pounds of cornstarch to start.

Did you try making oobleck? I’d love to see pictures of your experiment! Email me at jbelden@kckpl.org to let me know how your oobleck turned out!