From toddlers discovering their shadows, to physicists experimenting with fiber optics and lasers, everyone is fascinated by light. We need it to see, and life on earth ultimately depends on the light of the sun to survive. This week, Kindergarteners and 2nd graders are exploring the behavior of light and materials that can reflect or change the color of light. If you have a flashlight at home, or a flashlight app on a smartphone, you can make hand shadows like the ones below, or make up your own. See if you can figure out how to make the shadows larger and smaller.
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One of the things I plan on doing with this blog is sharing some of the activities that we do in the science lab that can also be done at home. Today I want to share an activity that I did recently with our 2nd and 3rd graders, making something I call “Oobleck.” This is a mixture of cornstarch and water that is a non-Newtonian fluid, which means it doesn’t act like a normal liquid. You can tap it, and squeeze it, and it acts like a solid as long as your hands keep moving. If you hold your hand still, the stuff starts acting like a liquid, and drips through your fingers. Cornstarch is made of chains of atoms so long that they get tangled if pushed on too quickly, like a bowl of cooked spaghetti. It’s so weird and surprising and fun. I call it Oobleck, because Dr. Seuss wrote a wonderful book called “Bartholomew and the Oobleck,” in which gooey stuff falls from the sky. If you don’t have it, you can probably find a copy at the library. To make Oobleck, you’ll need to pour some cornstarch into a big bowl. Use at least one pound. Run your hands through it so you can feel its texture. It feels different from flour. Start adding water gradually, and mix in the water with your hands. Keep adding water and mixing it until you have a very thick paste. You’ll end up using about a half cup of water for each cup of cornstarch. Now you get to experiment with it. Can you make a ball of it? What happens when you crack the ball in half? Can you make it ask like both a liquid and a solid? Can someone run across a bathtub full of it? (hint: check YouTube.) When it’s time to clean up, put as much of it as possible in a plastic bag, tie the bag, and throw it in the garbage. Pouring a lot of Oobleck down the sink might clog the drain. I don’t recommend trying to save the Oobleck for another day, since it can get moldy. Just get more cornstarch, and make more Oobleck. |
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May 2022
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