What You'll Need:
- Large bowl
- Food coloring
What To Do:
- Put 1 cup of water and 1½ cups of cornstarch in the bowl and stir to combine. Add food coloring.
- Notice that the harder you try to stir, the more difficult stirring becomes. (Slowly add more cornstarch if the mixture is too thin.)
- Stop stirring and quickly poke the oobleck with your finger. Notice that it feels solid.
- Slowly dip a finger into the oobleck. Now it feels like a liquid!
- Take some oobleck and roll it into a ball. Keep rolling, because when you stop, it’ll melt before your eyes!
Oobleck is a substance, like quicksand, that acts like a solid sometimes and like a liquid other times. That’s because cornstarch is made up of many molecules. When left alone, the molecules spread apart in the water. But when you apply pressure, the molecules squish together, and the mixture feels like a solid (so you can roll it into a ball). When you stop squashing those molecules, they spread back out and move through the water like a liquid again. If you threw some oobleck at the wall, it would hit the wall, bounce off, and then ooze into a puddle. Wild!
Our expert: Caitlin Drechsler, 5th and 6th grade science teacher at Buckingham Browne & Nichols in Cambridge, MA