RSS (Real Simple Syndication) is a way to subscribe to website updates. Using software called a feed reader, you can receive notifications whenever there's an update to Evans School News and Announcements or any other website that supports RSS. Commonly used feed readers include the web-based Google Reader, NetNewsWire for the Mac, and FeedDemon for Windows. Feed reading is also included in the Firefox web browser.
If you'd like to learn more, Webmonkey has a great write-up on RSS.