Start Over Button

Is there a way to disable the Start Over Button? In my opinion, I think this feature is the worst thing to be added to Khan Academy. I use Khan Academy daily as a Junior High Math Teacher with Math Support students. I assign them practice problems and videos over what we are doing in class each day. Since this feature was added, I have kids that hit it any MULTIPLE times a day during a class period. I would like to be able to disable it so my students have to go through the practice questions and not be able to start over after one question is missed.