When do I use the Approve/Deny function?

Approve and Deny should be the last item completed on an assignment by a SAI/AI.  It is basically the final decision by the instructor.  It cannot be undone, only changed from deny to approve.  You can change it at the bottom of the cadet assignment while in instructor view.  While reviewing the cadet work, if you are not satisfied with it, the next step would be to type in the feedback at the bottom, select the Send Feedback, and then select the blue colored text right above the box that says Change to In Progress.  This will allow the student to get feedback that you changed it from complete to in progress and why.  This will also change the % completed on your dashboard tile for the assignment.  Once they complete the redo, it will show complete back on your dashboard for review.  Once you are ready to give the go/no go (Approve/Deny) then select that for the final decision.