Please add an alert of some sort to warn teachers whenever they try to change an existing Assign To field in an assignment or quiz by removing a student or set of students from the list after student work has occurred in the activity (submission or quiz attempt). The result of the change is the apparent deletion of all the existing submissions or attempts, and a great deal of panic and stress. This is particularly a problem when teachers mistakenly replace the existing set of students - e.g. "Everyone" - with an individual student when they are giving that student an extension on the activity. While the submissions will reappear once the Assign To field is properly reconfigured, the effect of the error is traumatic and can be prevented with a simple alert.