If you have Teacher or Manager access to a course, you can "Switch role to..." another type of user to see the course from their perspective.
Most often, instructors will use this feature to see their course as it might appear to their Students.
As of Moodle 3.2, the "Switch role to..." link can be found on the user menu:
Note that the accuracy of what you see as another user may be affected greatly if your course uses Groups and Groupings.