It encourages school kids to create their own levels in the game, and to better understand the science involved. PC and Mac versions of Portal go free for now.
Check out the video below as the Evergreen School visits Valve to better understand the science involved with all those portals. The free weekend to coincide with the program ends September 20th but until then PC and Mac gamers can enjoy free Portal antics.
'Learn with Portals' iniative has Portal free for entire weekend
16 September 2011 | By Simon Priest