Pour 1 pound of cornstarch into a large bowl. Add about 1 cup of water and mix it in with your hands or a sturdy spoon. Gradually add water, about ¼ cup at a time, mixing thoroughly after each addition of water. Keep adding water and mixing until it is very thick, like molasses or honey. Now your oobleck is ready. Poke the surface slowly with your finger - it’s a liquid and your finger goes right through it. Now poke it quickly - tap on the surface. It feels like a solid! What?! Grab enough oobleck to make a ball in your hand, and pass it back and forth between your hands like a hot potato. Crack the ball in half, since it’s a solid. The halves melt, since they are also a liquid.
What’s going on? This is a non-Newtonian fluid - meaning it isn’t like other liquids. Cornstarch molecules are long chains, like a bowl of spaghetti. When you squeeze them suddenly, they get jammed up because of friction. If you poke it slowly, the strands have time to get out of your way.
Oobleck can be stored for a few days in a covered container in the refrigerator, and after that it tends to get moldy. Throw used oobleck in the trash, not down the drain. Please try making oobleck - it is truly amazing.
I’d like to end this post with a big thank you to the parents from the OPS PTS who have been helping getting our school garden ready for winter.