We also give them many other privileges including being able to see problem sets while they are still hidden so that they can help with checking homework sets.
We also keep
record_answers_when_acting_as_student => undef
which means that no-one (including professors) can record answers for the student -- even when
"acting as" the student.
While this occasionally surprises instructors trying to give a student credit for a problem
I think it is wise to keep the student record "pure".
Hope this helps.
-- Mike