For a limited time only Valve will be making the PC version of “Portal” free. You can get the game for free until September 20, 2011.

The deal is on the site “learn with portals” which talks about how Portal intrigue, engage and inspire people.

To show how the game inspires people, students from the Evergreen School visited Valve.

For more information and to download the game head on over to http://www.learnwithportals.com/.