Q. How do I see if a student has looked at a specific file/reading?

Looking at individual students

1. Go into the course and select People from the left-side menu
2. Click on a student's name
3. in the sidebar that opens up click on their name again
4. From the right-sided menu choose Access Report

Course Analytics

Another option is to use the Course Analytics 

1. Go into the course and select Course Analytics from the right-side menu
2. Select Weekly Online Activity
3. Click on the email icon
4. Then you could view or message students who Viewed, Didn't View, Participated, or Didn't Participate in a particular resource