This block is devoted to track supervised sessions, where students work on the site in classroom under teacher (or staff) supervision. The session can have it's type (lesson type), classroom and group of students.
The classroom is defined via IP subnet, so students off class won't be recorded as participating in sessions.
The block allows you to see logs on what is going in each particular session.
More importantly, you can control students permissions, given them special abilities (like attempting exam quiz) only during supervised sessions. For now there is quiz access control rule, allowing you to restrict quiz access to supervised sessions. There will be more options later.