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

Our Church has a Laser Firearms Training Simulator. We use it, not only for our Safety Personnel, but also in a 1 1/2 Day Firearms Safety Course for Ladies and for State Certification. Two weeks after taking our training, one of the ladies said that, shortly after her husband left the house in the country, someone walked up to the door and tried the door knob. She suspected that it was a local Meth User, looking for something to pawn.

She said that she was scared, but not in a panic. She went to the gun safe, obtained a pistol, retreated to a defendable position of safety, and called her husband. She said that, without the Scenario Training that she had gone through, she would have had no "S.O.P." to adapt to the situation.

So what I am saying is that by having SELECTIVELY Armed Staff in Schools, it will make them much harder targets. Throwing guns to teachers without training makes as much sense as throwing M-4's at untrained Recruits and putting them into Combat.

But look back at the early days of Israel. "Palestine" had been under the authority of Great Britain, and so prohibited private firearms ownership, much like Britain. When Israel was first formed, they continued that tradition. In the 1950's and 1960's, the busses and sidewalk cafés of Israel were constant targets for AK-carrying terrorists. Israel changed from keeping the citizens without arms to allowing a sizeable percentage to own and carry concealed weapons.

It took about three incidents of terrorists becoming well ventilated, to immediately reduce the cowardly attacks on formerly unarmed victims. I recall a report of about 4 terrorists attacking a sidewalk café, and they found that they had placed themselves into an L-Shaped Ambush. The lone surviving terrorist said, "We didn't know that they were going to have guns...……………"

Area security is more than giving someone a sidearm, even if the person is a skilled marksman. I can only imagine what it would be like, if I never was trained to fight in the condition where it is dark or little light, had no idea who the shooter or shooters are, where they are, and a bunch of people running around screaming, knocking things over, etc. and not sure my weapon will fire, because I haven't fired it or cleaned it in over 6 mos. Having teachers carry sidearms is a foolish security measure.

In over a year at Camp Leatherneck with 100% of the personnel being armed, there wasn't a single person shot within the camp, which was drastically safer than where I live now in DC, where guns are prohibited.

Some say it's the increased availability of guns, but since everyone had weapons in Leatherneck, and guns were allowed at school in my parents generation, I don't think it's that.

Some say this is because we were all trained, but most of us had only actually fired the weapon during a single 4-hour qualification, so I don't think it's that.

Some say this was because we were all subject to the UCMJ, but when increased penalties for gun crimes are suggested, my neighboring city dwellers cry "racism," so I don't think it's that.

Some say that military members have a higher standard of morality, but then decry the "rape culture" of the military, so I don't think it's that.

Some say it's the lack of police enforcement, but during my time in DC and my time at Leatherneck, I have never seen any enforcement of any rule or law by police, so I don't think it's that.

So the question still remains: in a society where guns are legally available to a smaller percentage of the population than almost any time in history, what is driving this increase in shootings?

What is realistic is that anyone who is familiar with a pistol has a better chance of stopping a shooter than an unarmed person would. Hiding in your room, when someone walks in firing a rifle, you do not have to worry about other armed teachers or police officers, you do your best to take out the threat. Without the pistol, you are reduced to throwing books, using a fire extinguisher, or just cowering in the corner. So, yes it is realistic, IF you want to improve your child's chances of surviving an active shooter incident.

The training the teachers receive has nothing to do with an offensive move on an active shooter, no closing on the shooter and firing a well aimed shot without putting anyone else in danger, more barricade and protect. So in answer to your original question, is it possible, yes.

Politic's has a great deal to do with this narrative as well as the Media, we have destroyed the Nuclear family with social justice and welfare programs that no one is responsible for their actions, dads no longer care for their families and protect their children. The Department of Education has left young men behind in the education gap regardless of race since the early sixties and never looked back; common core curriculum is total B.S. and does little to educate or children about anything but an agenda of political change. We need real men to step up to the plate and teach real American values to our children today; start with the Ten Commandments handed down to us by God, yes I said God. They are the basis of a free and great society equal to all, and if anyone is offended by this statement, that is a shame, because God gives us the right to be free, defend ourselves and families, stand up to Tyranny, and help those in need. I have yet to see one Politician, or Teachers Union provide squat, so if our Government, and Teachers cannot provide for he rule of law and safety, educate our children to treat one another with respect, then I challenge each and everyone of you, my brothers and sisters in arms to take up the cause and educate the kids. Maybe it does take a Village to turn this mess around!!

With training, yes. One example.

SGT Alvin York captured a large number of Germans Soldiers singled handed with just his M1911. Then there were the Machinegun nest he silenced.....

Yes. Simple demonstration. Go play with sim rounds and make an entry into room with your AR. The defender has the advantage of positioning and knowledge of the room.
Thats why urban warfare is horribly costly for attacking armies. Ask any of your infantry friends who have SNCOs from Fallujah how nerve racking being the first one in the door is.

In a face-to-face confrontation, no. But there are several things a proficient handgunner has over some shitbag with an AR-15:
1. Surprise. Shitbag can't see through walls, and you will be able to judge the location of the shooter by observing the reactions of the victims. He can't determine your location until you pop a cap in his ass.
2. Terrain. Many (most) active shooter incidents are in enclosed spaces. This negates the primary advantage of a rifle as a medium range weapon. Indoors presents lots of concealment.
3. Training. I did say "proficient" handgunner. I went through Gunsite Academy earlier this year with two teachers (one from Oklahoma, one from Texas). Instructors told us at the end of day 3 that we were better than most SWAT Officers.
4. More training. Some teachers are former military, who have received weeks/months/years of intense combat training that shitbag didn't get. It is highly unlikely that the shitbag has military or tactical training (I'm referring to the real thing, not watching Rambo on DVD). He won't know how to properly clear a room, and thanks to Hollywood, he'll do it wrong, which give you the advantage. Since he doesn't have advanced tactical knowledge, he's operating at a disadvantage.
5. Still more training. More schools and local police departments are training for Active Shooter scenarios. Not enough in my opinion, but it's changing. Look at two of the last three mass shootings (as of 08/05/19) - police responded within 2 minutes (30 seconds in Dayton) to neutralize the threat. The El Paso Walmart incident took longer. Police response times and efficacy are improving every year.
6. Attitude. Teachers are [presumed] intelligent people. If they've chosen to take the training and chosen to carry a weapon to defend the children, I certainly hope they have the attitude to engage with no holds barred, with pure naked aggression, to win the fight, and that they've analyzed their decision and have the heart to unleash their inner beast.

Two different tools. An AR in most builds is for distances (exceptions of course for an AR 15 built as a pistol,like mine) however a handgun is distances associated with close quarters. If the gunman has high ground with a line of sight exceeding 50 feet unimpaired, the teacher with a sidearm should shelter in place and not engage an Active Shooter. However if this inside, short lines of sight, then the teacher has more mobility and a slight advantage assuming their shooting skills are similar (or lucky... sometimes its better to be lucky than good).