Yep, and if just the teacher had had a gun, the gunman would have just shot him first before he could react.
Well the NRA argument is that having guns means they can overthrow the government if they get too big for their boots. Because obviously if the government can do what they want, they aren't answerable to their citizens. Makes sense to an extent, but I'm not sure that having handguns would really give the citizens a chance against soldiers with full auto rifles, Apache helicopters, artillery etc. Maybe having more than two political parties would help more.