This is very interesting! Google has a whole page dedicated to search education tools - i.e. lesson plans geared towards teaching people how to use Google. While it's necessarily a bit Google-promoting, some of it could be pretty useful. It's primarily geared towards k-12, but some of the lessons could certainly be used with our lower level students who haven't had as much exposure to web-searching. The video "How Google Works" is also pretty good, except for the second half which is a bit propoganda-ish. But the beginning information about how Google indexes the web is a nice explanation.