Teachers may see AA or AD indicators in their Grade Book with student's Attendance:
These indicators are so the teacher knows that the student was absent on one of two days:
Absent when Assigned (AA)
Absent when Due (AD)
If the teacher is going through their grade book later and can't remember why the student didn't turn in the the assignment, they can easily see if they might have missed it because they were absent on the assigned or due date.