When the teacher's aid invokes the TA version of the Grader, an interface similiar to the instructors appears on the screen. The roster, settings, and categories menus are removed. This disables these options for the TA.

This display is similiar to the instructors except that the options to add, delete, and modify students and columns has been disabled. More information can be found here.

This allows for the teacher's aid to modify grades in the gradebook, without the worry of deleting or adding students or columns.