It would be very very helpful for students to have a dashboard type widget for the current course they are viewing. Eg a quick summary of important course information would really improve the interface.
1. Icon driven links to Unit Overview/Notifications/Workbook/Grades/Discussion/Course Info/User Settings/Withdraw
2. At a glance status eg Current Grade/ Percent Complete/ Pass Fail on Units or Modules
3. Make the Course Structure Navigable for Logged in Users so that they can jump to a module for review.
Attached is a mockup of what all of these together might look like (just for illustration, im sure you can design better.