Waylou has a great article entitled "10 Things You Need to Know About Google Plus". Google Plus is a great resource for education. There are some great functions and it isn't cluttered with apps and games. You can easily create Circles (groups of people) and selectively share what you want with different groups. Hangouts let you have video conferencing (free) which can be used for study groups and more. I really like Google Plus. This article has some great information about the features and uses of Google Plus.
I highly recommend the article, and Google Plus, for educators.