When a student signs-in to their account on your course website and clicks to start or continue they are taken to the Lesson Viewer.
If they're just starting your course they'll be taken to the first lesson. Or if they returned to continue they'll be taken to the lesson where they left off.
The current section is expanded and the current lesson is highlighted in the left menu bar. The student can jump around between lessons by expanding sections and clicking the name of a lesson.
Marking lessons as completed
If a lesson contains a single video it will be marked as complete automatically after the student watches 95% of it.
If a lesson contains a single quiz or test it will be marked as complete when answers to the questions are submitted.
Otherwise students need to manually mark a lesson as complete after they've finished taking it. For example, if a lesson contains just text, a few PDFs and some images then the student should mark it as complete after they have viewed, read and understand the material.
Lessons can be marked as complete by clicking any of the 3 icons pointed out in the screenshot below.
A completed lesson will show with a check icon and a line through its name in the sidebar. It will also display as completed in the two other spots described above.