This week's challenge was to classify ooblek (roughly 2 parts cornstarch to one part water) as a solid, liquid, or gas. Pretty easy, right? Wrong! Ooblek belongs to an unusual class of liquids that become solid when subjected to sudden pressure or force. As it happens quicksand behaves remarkably similarly to ooblek, which comes in handy if you're an ooblek expert asked to consult on the best way to escape from quicksand. To thrash or not to thrash? The kids submerged action figures and plastic animals in the ooblek and compared the reults of rescuing them using quick movements versus slow movements. Their recommendation: Move slowly and don't panic. Thrashing around simply causes the ooblek (or quicksand) to solidify, making it even harder to get free.