Staff can see a student preview of their subjects/communities without requiring a separate login to the LMS.
Student Preview is more powerful than just turning Edit Mode off. Staff are able to submit assignments and complete tests as students, as well as to interact with collaboration and communication tools such as blogs, wikis and discussion boards. All data generated by Student Preview, such as assignment submissions, is retained by the LMS subject. Importantly, Student Preview is available to staff even if the subject is not yet available to enrolled students.
Take a look at the Student Preview guide for more information.