Schoology is an application for communications, school management. There is no restriction, you can use schoology to talk whoever you want in this website.
Click course, you can view what course you take.
The resources function help you know all the information and knowledge from the course you take.
Grades can help you to check the grades you get from the courses you take.
This is for people to look at the upcoming events and assignments. So they will not forget to do or prepare for their assignments or activities.
This is for people to add friends, when you are friends, you can know what courses they take and talk to them.