The difference between pages & groups: Pages allow people to maintain a personal-professional distinction on Facebook but are generally public. Pages do not display their admins names. However, when you post to a group, these actions appear to come from you as an individual. If you post or take other actions on a page you won it will appear to come from to come from the page. Groups can be kept closed.
Notes are like blogs. Publish thoughts about class content. If you like, you can tag students in the notes.
Blogs are much longer than tweets. It is interactive.
Twitter has a PM function although it is mainly used for public postings. Edmodo is a newer site that does the same thing as twitter.
