You could industrialize the security industry if you don't want to go the train-up-a-teacher-or-two-to-police-standards (psych/background checks included).
We have about 400 000 returned/returning veterans, a lot of them looking for work. Create an incentive for schools to get serious about this. The feds could build a few academies around the country, Iraq/Afghanistan vets could undergo some re-training and refreshing of psych checks and all, and land a good job. Win win.
You don't want to get quite Israel with all this stuff, the public's not of the same mentality, but you could definitely do something in a security sense. More than a mall cop, but not quite at the point where you have teachers carrying either. One or two designated, highly-trained, school-protection-is-my-career guys or girls per school. It's not a total fix to the problem, but can't hurt so long as you're doing it responsibly and putting these security types through pretty rigorous mental checks to land the gig.