I ran two back to back workshops for the Faculty Summer Institute at UIUC on May 20, 2014.
The first was an introduction to Google Plus in general. Many of the slides are from Google's open source of information.
The second was an introduction to Google Hangouts on Air for education. What you won't find are step by step info on how to set one up since we did that live.
Clipping is a handy way to collect important slides you want to go back to later.