Is it realistic to believe that a teacher could effectively defend against an active shooter, using an AR-15, armed with only a handgun?

A police officer in Maryland did. If the teacher trains regularly with the handgun he or she could. There are programs with many law enforcement training academies or headquarters that include what the Maricopa County, AZ sheriff's Department referred to as FATS (firearms training scenarios) or the video game for short. They reenact real events that took place across the country. A good trainer can branch the progress of the training event in several directions depending on the deputy's initial reaction and subsequent acts to the scenario. Its realistic as hell. We often exited the training session with a full sweat and the shakes. The training pistol is pneumatically operated and connected to the controlling computer to record the location of hits or misses, the pneumatic system makes the gun recoil realistically so the shooter has to reacquire his sight picture. It also gives the sound of the shot along with the recoil. Its so realistic that when an officer attends a session as part of regular firearms qualification, he is only allowed into the training studio with an empty holster and no backup weapon. I'm told that there was once an incident where the scenario included a stress magazine change and the deputy dropped the magazine. Went to his hideout and holes appeared in the video screen. I think if the selected school staff and or faculty attended sessions like that regularly they would be well qualified to carry in school.

There are plenty of examples of handgun-armed good guys taking out rifle-armed bad guys: The FBI Miami Firefight of 1986 (S&W M459 9mms and .357 Mag revolvers vs. a Ruger Mini-14), the 1989 Lozano Riots in Miami (Miami PD officer shot a sniper at 200 feet with his Glock 19), and the Fairchild AFB incident (USAF Security Police Senior Airman Andy Brown took down a MAK-90--wielding active shooter at 50+ yards with two hits out of four shots from his Beretta M9).

It doesn't matter if you're military, civilian law enforcement, or an armed private citizen; with the right equipment and right TRAINING AND MINDSET, you can win.

The person being at the right time and the right place and a tool can win. The story of David and Goliath is real.

Yes. A properly trained teacher with a good handgun and within distance parameters could take out a bad guy with a scary AR. Just as long as there are not a big crowd of panicking people.

In the close confines of a school building? It is realistic to believe a person could engage a suspect armed with a rifle and prevail with a handgun. Can it be done without placing students or other people at risk? Probably not. Nor, can law enforcement enter a building under this scenario without placing innocents at risk.

A better chance than without one. The hallway is a poor place to deal with this. You would have to make the killer come into the classroom. His movements would be limited by the doorframe. At that point, it would depend upon your angle to the shooter. In one school that I taught in, I would have let my students blaze it out. What Gun-Free Zone? We teachers were the only ones unarmed.

It's never been tried before so therefore no one knows the results until it is placed into action. "Do nothing and nothing gets done"

Clint could!!!

LCpl Timothy McCain I have posted similar questions. For me, the answer is no. I doubt if individuals went to college, attended teacher credentialing classes, attended state EOG update classes, attended classes to be guided on how to work with special needs students, crawl through Mount Everest high student loans to compete in a gunfight with a mad trigger happy assailant.

Or the could just end up shooting kids like the cops. How about we just put metal detectors in schools