We used to make oobleck all the time in high school, though we didn't have a name for it. We just always called it non-Newtonian fluid. For creative kids, we could have done better. Part of the appeal is that it's pretty weird stuff, and it's insanely easy to make. You literally combine the cornstarch and water, and you're done -- no need to let it set, no cooling, just mix and go.

And, once you've made it, you can do some cool things. Check out this crazy video of oobleck on a subwoofer. And, because it's every kid's fantasy once you've fooled around with this stuff, this video of people playing with a whole frigging pool of it.