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

Anything is 'possible' and even realistic but perhaps not so probable.

You forget that you are going up against a Coward and a bully who does not have any training, they expect to gun down fleeing or cowering people who are terrified of a gun. The teacher would not be expected to hunt down the shooter only to guard their door. In all these shootings how many people died after the shooter was faced with ANYONE with a gun. The last shooter was stopped by Young man who stood up to him refusing to let him go even after he had been shot, think what he could have done if he had been allowed to carry a gun to defend himself.
You must remember that these news cowards are only after publicity to get their name out. They need to be put down and hard. And their name never listed except on their grave stone.
A gun is a tool nothing more nothing less. Its how the PERSON uses it that counts.

As opposed to what? Throwing erasers or magic markers at the shooter? If the teacher is protecting her/his classroom, no confrontation is necessary unless the shooter comes to the door of that room - in which case a pistol can be very effective. If the teacher goes out to confront the shooter, the shooter may, at the very least, get pinned down until more help can arrive. I don’t, of course, believe the teacher should do something foolish, but keeping the shooter from moving around freely (from a relatively safe position) could save many lives.

lcpl:

Thank you for your service.

Is it much more realistic to believe that

1) a well trained, armed school employee could effectively defend against an active shooter, using an AR-15

than it is that

2) an un trained, unarmed school employee could effectively defend against an active shooter, using an AR-15

I am not a gun guy, but a weapons trained friend of mine stated "When seconds matter, the police will be there in minutes."

It could, hardly, be more true or more simple.

The only person who ever out shot me on the range was a female, so can they learn to shot and do so accurately, YES they can. Second we had a short 5'1" 2LT female officer at Fort Sam Houston at one time, she had pulled aa as I reached down civilian who was traveling through post, pre 9/11, for speeding. She approached the car and asked him for his Drivers License, Registration and proof of Insurance, he looked at her and immediately got mouthy, not a good idea. When she told him to step out of his car he started to laugh at her, she reached through his window and proceed to pull him out the drivers side window and put him face first on the ground with her knew centered on his spine and all 130 pounds of her weight and been dropped on his spine, he was not moving. She saw me roll up and motioned for me to come on over. I had been sitting back about 80 feet as per dispatch instructions. I exited my vehicle reached around behind me to my hand cuffs and as I reach down to cuff him two SAPD Units also rolled up and out came two of the biggest female Police Officers I had ever seen. he was wrapped and tagged put in the 2LT's unit and escorted to the PMO. Do I think any teacher can handle such a situation yes I do, what most do not understand those teachers who undertake this responsibility also undergo continuous training to meet the state standards and retain qualification. We have two School Districts here in CO that have armed teachers and no-one but certain members of the County Board know who they are. They undergo emergency response training for three months during Summer Break at one of the Police Academy's in state.

A handgun beats an eraser any day …

I was a teacher. As retired army, with boo-koo weapons training and frequent sustainment training on the range, I would have successfully defended my students if I had too. But, it was not my plan to close with and kill the enemy. My plan was to stay in my room and defend my students if needed. I am certain that I could fire 2 or 3 well placed rounds into the shooter if he came thru my door. There are too many unknown and uncontrollable factors, as you stated above, to close with and destroy the enemy. Just one possible problem is the police might mistake me for the active shooter. So, if say, 25% of the teachers are voluntarily armed, and it is known that some teachers are armed, and nobody knows which teachers are armed, then I suggest that it is safe to say that school is safe from an attack. Even a crazy person will seek out another target. And like the old saying, I don't have to run faster than the bear, I only have to run faster than you.

I think will you for getting is that scenario most likely will never happen because criminals are cowards. If the average criminal knows and understands they he will be immediately confronted with an equal amount of firepower or resistance they would not even attempt to rob or cause mayhem in that particular building or area.
It's more a psychological defense than an offense. I'm all for arming teachers in the classroom because it will serve a 2 fold purpose. It will serve notice to the unruly students in the schools that always seemed to make YouTube videos of them fighting and physically assaulting teachers that will come to a screeching halt. And to when they leave school and they go tell their criminal friends at the teacher who their ass with the butt of a 9 mm, their criminal friends will go look for something else to do, like get a job !

1st, I think you would be surprised to learn how many teachers a veterans or already have a concealed carry permit. To answer you question directly, I don’t think many would run out to track down the shooter, but they could absolutely protect their classroom if the shooter tried to come through the door.

Absolutely not! I do believe that an active shooter needs to be engaged and put down as soon as possible, but not by the teacher. A more viable plan is to harden the classroom by being able to lock a substantial classroom door to prevent the shooter from freely moving from child to child. After 911 the response was not to arm flight attendants, but to prevent access to the cockpit by hardening the door and preventing a bigger tragedy from occurring if the terrorist were to gain control of the plane. Active shooter drills should be performed in schools and police should regularly practice in schools within their assigned areas; we train as we fight! Being a career infantryman I have seen professional soldiers injured during live fire training and combat, accidental discharges clearing weapons, and just plain stupidity by soldiers who train for a living. I don't want anyone with only a few hours of training and not years of continuous, realistic training anywhere near a school full of children with a gun. A teacher should teach and not try to engage an armed opponent in a classroom or hallway full of children; get as many children locked away from the shooting while law enforcement aggressively confronts the shooter and rolls him up.