Required by whom?
I think it would be easy to make the case that the School itself encouraged this behavior through their one sided propaganda and willingness to allow the children to leave school during a time they were “LegallY responsible for their welfare. Their blatant irrational hostility towards guns is self evident of the hostility they purposely created against law abiding citizens that own guns.
Depends on how far the parents are willing to go, if at all.