When Andy, Emma or any student logs into the course they see a help button on the top right corner. Clicking on it explains to them how the completion (progress) tracking system works:
If it's been switched on by admin, then students will get either a dotted check or a blank box next to each activity.
A dotted check mark is one they can manually click on to mark an activity complete when they feel it's done
A blank box will automatically show a check when Moodle decides the activity is completed. If a student moves the cursor over the blank box it will show not completed.
If we take a look at student Andy's view when he starts the course, we can see this in action next to the Read This first! page. In the next screenshot, I've drawn a square around the blank box as it's difficult to see on some themes. With the cursor hovered over it, it tells me this activity hasn't yet been classed as complete:
If Andy goes and reads (views) the page, the box will...