You can check on student activity from the Navigation block

1. From within you unit, go to the Navigation block. (located on the left)
2. Click Participants.
3. Last access column shows the time elapsed since a user has accessed that particular unit only.
4. Assign Inactive for more than from the available options to check for users who have been inactive for that specified period of time.

Other resources:

• Quick Guide
• Register for a Training workshop