This is something the boys have wanted to do since they watched this video on YouTube:
Most liquids follow certain properties and are known as Newtonian fluids (after Sir Isaac Newton). Today we had a super fun time learning about non-Newtonian fluids. I won’t try to go into detail about what Newtonian and non-Newtonian fluids are in this post because there are lots of sites on the internet that can explain that better and more completely than I can. But, very simply, non-Newtonian fluids behave differently than typical liquids because they have a variable viscosity. They behave differently depending on the amount of stress they are under. We made a cornstarch and water mixture that will flow like a liquid when resting or touched gently, but if put under more stress, such as a hard smack it behaves like a solid. Other non-Newtonian fluids are ketchup, silly putty, and toothpaste.
This is a really simple and fun activity for kids. We started with 1/4 cup of cornstarch in a bowl and added small amounts of water to it until we could stir it but felt some resistance. When you pick it up in your hands and squeeze, it will become more solid, but then when you open your hand it will flow like a thick liquid. Be sure to have extra cornstarch on hand if you need it for dinner, because we went through almost an entire box today. You can click on the pictures below for a larger view of our Oobleck as the boys played with it.
I’m really glad I waited until the warmer weather because this is one experiment that I would not want to do inside the house. Another note is that you don’t want to put this mixture down your drain, if there is any left-over stick it in a bag in the trash, after a while the water will be removed and it will become a solid again.
We did just the basics, but if you are brave and have an extra sub-woofer lying around, try putting the cornstarch mixture on the sub-woofer, turn on some bass beats and watch the show. Make a few small batches with different colored food-coloring to see how the colors mix. Even if you don’t teach the science behind it, kids love this stuff. So go ahead, give it a try!