Better yet, give the teacher a gun and when that muffled gun takes aim, the teacher blows his head off and no children are killed.
I am looking at this the way banks have tellers with silent panic buttons that notify those with guns there is a hold up in progress. I agree that the more teachers with guns, the better. But not all teachers will get guns and the training to use them. I say give the panic buttons to the teachers who are not equipped with guns. Those in the immediate area with guns can still take out the shooter.