If you want to grade assignments without knowing who submitted them, you can hide student names in SpeedGrader for anonymous grading. Hiding student names is done on a per-assignment basis.
If you want to hide student names for all assignments in a course, learn how to manage feature options in the course features lesson.
Note: Hiding names in SpeedGrader does not affect names in the Gradebook and must be done separately. Learn how to hide student names in the Gradebook.
Hide Student Names
To hide the student names, click the checkbox next to Hide student names in the SpeedGrader.