Sunday, March 7, 2010


What is this stuff? Is it glue? Is it yogurt? Is it some particularly low-budget brand of Play-Doh?'s Oobleck!

This is a story activity based on Bartholomew and the Oobleck by Dr. Seuss. In the story, a page named Bartholomew Cubbins must save the day when the king decides he's tired of all the "usual" things that fall from the sky, and asks his magicians to conjure up an all-new substance: "Oobleck." The gooey Oobleck starts clogging up everything and wreaking all kinds of havoc, until Bartholomew comes up with a very simple solution to end the whole mess.....

You can make your own "Oobleck," and it is strange, intriguing stuff. Technically, it is a "non-newtonian fluid," which means that it acts like both a solid and a liquid. When you pour it, it is liquid, but if any force is applied to it, it acts like a solid. So you can squeeze it, and it will feel completely dry; but the second you release your grip, it becomes liquid again!

Or you can run a fork through it, and you'll get dryish scratch marks,
but the second you lift the fork, all the Oobleck will ooze back together as if the scratch marks were never there : a little like that wet sand right at the water's edge on the beach.

According to my friend Wikipedia, this is "due to polymers, which are long chains in the structure of Oobleck. When you hit Oobleck hard, the polymers tangle and resist the force. When you push something in it gently, the polymers have time to move, and it acts like a liquid." So there you have it.

We read the book and then made our own Oobleck; it is messy, and you may hyperventilate slightly during the activity, but you will be pleased by how easily it cleans up with water.

Recipe for "Oobleck"

-- 2 cups cornstarch in a large mixing bowl
-- About 1 cup of water (add a little more, bit by bit, if you want a runnier Oobleck)
-- a few drops of green food coloring so it will be green like the Oobleck in the book

Drop a few drops of food coloring into your water. Then, stir the water into the cornstarch with a fork until it is about as thick as pancake batter. I preferred ours a little on the thicker side.

Set your kids up with a bowl of Oobleck and some spoons, forks, whatever you like -- they will be pretty surprised -- this ain't their mama's Play-Doh!

Further Oobleckiness:

Here is a rather entertaining, 4 1/2-minute clip from the show "Mythbusters," in which an Oobleck-style experiment (though not mentioned by its literary name) was done on a larger scale, using 200 gallons of water and 1,000 pounds of cornstarch. The segment includes a good explanation of how a non-newtonian fluid works. Adam (a "mythbuster") is able to run back and forth across the surface of what looks like a regular ol' liquid. Older kids (maybe 4 and above) will enjoy this.
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