Yeah, I teach at a private adult vocational school and we have one of those stupid signs that advertise that NO ONE IN THIS BUILDING IS ARMED, SO YOU CAN COME IN A SHOOT AT RANDOM, AND NO ONE WILL BE ABLE TO STOP YOU . . . ya' know what I mean?
Would rather have a sign indicating that someone, somewhere in this building is armed and ready to use his weapon.
People keep talking about the actual event of shooting back at one of these nutjobs, etc. but what is overlooked repeatedly is the deterrent value of just having the possibility of armed 'resistors' in the schools. Your sign would be the way to go.
These shooters want to kill lots of people and make a 'statement', then they want to die on their own terms (suicide). They don't want to be wounded, taken alive to stand trial or end up in a mental ward. They want to die by their own hand, the ultimate 'control', and in their own minds as some sort of 'legend' with the publicity that attends such a reputation, even if it is the worst sort. Just having the possibility of someone who can shoot back and mess up their plans is a deterrent and they'll look for the softest target. As examples: Columbine - shooters committed suicide; Dunlane - shooter committed suicide; VT - shooter committed suicide when he heard the cops breaking in downstairs, Newtown - shooter committed suicide when he heard police sirens; recent mall event - shooter committed suicide when he saw a weapon present in the hands of a guy carrying concealed who didn't even have to fire a shot. Deterrence - it works (not always, but more often than "Gun Free Zone").