This is a simple mixture of cornstarch and water. You may also hear it called “gak” or “oobleck.”

It creates a unique substance that acts like a solid when pressure is applied, but acts like a liquid if you stop applying pressure. Learn more at Steve Spangler Science and SciFun.

To make it: Start with clean hands, because you’ll mix it with your hands and you don’t want to introduce any germs to it. Pour some corn starch in a bowl. Add water a little at a time, mixing it with your hands to about the consistency of honey. Your goal is to create something that feels like a stiff liquid if you stir slowly, but solidifies when you tap on it. In class, we use a 16 ounce container of corn starch and add somewhere between one and two cups of water.

Note: you can also use other starches: potato starch, tapioca, arrowroot or baby powder. Learn more here: https://www.steampoweredfamily.com/activities/oobleck-science-fair-project/

Once you’ve made it, try these experiments:

• If you pick it up in your hands, you can roll it around quickly and make a solid ball, but when you stop moving your hands, it melts into liquid and dribbles out of your hand.
• You can stir it slowly like a liquid, but if you smack it with the spoon, it acts like a hard solid.
• If you make a plastic animal “run” quickly across it, it doesn’t sink in. If you move the animal slowly, it sinks into the “quicksand.” If you move the toy quickly like it’s struggling to get out, it stays stuck, but if you ease it out slowly, it breaks free.
• You can scoop some up in a slotted spoon, then let it ooze through the slots. Or us a colander or grate – anything with holes for it to ooze through.
• Drip on some food coloring and try to mix it in.
• If you have a dinosaur fan, call it La Brea Tar Pits and add some toy dinos.
• Hide lots of small plastic trinkets in it for a good workout of small motor muscles.
• Try the melting snowman oobleck game.
• Experiment with sound waves. If you put oobleck on a sub-woofer speaker and play music, the low frequency sounds waves create some super cool effects. Just google “dancing oobleck” for lots of videos. (I also wonder what would happen if you touched a back massager to a container of oobleck – would the vibrations cause cool effects?)
• Experiment with dry ice and oobleck. (I can’t find any good videos of this… here’s the best I found. Note: some of the other videos show people handling dry ice with bare hands – don’t do this. Use gloves or tongs.)

When you’re done with it: If you want to keep it to play with again, just put it in a ziplock bag. If you want to dispose of it, do NOT pour it down the drain!! It WILL clog your pipes. Just throw it in the trash. When cleaning your hands, scrape most of the goo residue into the trash before washing your hands.

More fun:

This substance is sometimes called oobleck in honor of Dr. Seuss’ book from 1949, Bartholomew and the Oobleck. So, that’s a great companion book to this experiment.

On the Ellen Show, they made a giant vat of this stuff that Ellen DeGeneres runs across. See it at www.youtube.com/watch?v=RUMX_b_m3Js.

On Emily’s Wonder Lab on Netflix, check out the episode called “Walking on Oobleck.” (Emily’s is a fun science series for kids that’s definitely worth checking out.)

More hands-on chemistry experiments.