As part of some sort of educational something or other, Valve is offering Portal 1 for free on Steam, for Mac or PC, until Tuesday. If you don't know what Portal is, what's wrong with you? It was an almost throwaway spatial-reasoning puzzle game added on to to 2007's Orange Box, which became a sleeper hit by virtue of being both funny and awesome. It's a great game, even if you're not a gamer.

We absolutely buy the notion that Portal is educational gold, making "physics, math, logic, spatial reasoning, probability, and problem-solving interesting, cool, and fun," and cheers to Valve for making it available for free—but this video is a little depressing when you realize that all the kids are $20K/year "highly capable" private schoolers who almost certainly don't need a leg up. (Then again, we finally got around to seeing Waiting for Superman last weekend, so maybe we're just bitter.)

It's not the first time they've done this, and it might not be the last, but you never know, right? Go get it now.

The Stranger Testing Department is Rob Lightner and Paul Hughes.