An excellent PDF explaining how to get the most out of Google Search. A good idea might be to print out a few copies of this and put it on the wall near your desktop computers? Similar posters relating to other google tools can be found here: http://www.google.com/educators/posters.html
Check out this page with lots of other google search options & also great tools to assist learning. I especially like the 'Wonder Wheel' to help mindmap your search.