Last May I blogged about the educational applications of Valve's Portal 2, for PlayStation 3 and XBox 360:
This week, Valve, Portal's publisher, launched the site Learn With Portals. Valve is also offering Portal for free for both PC and Mac! The offer ends September 20th. Here's the link: http://store.steampowered.com/app/400/. I just downloaded it for my Mac.
Portal is a single-player game that applies authentic physics, mathematics, and technology concepts. It's an excellent addition to any math or science classroom. Check out the video below: