Items like that showed up many years ago as clipboards for cops. Then clipboards for school kids. Then as backpack inserts for school kids. All pretty much a 1/4-inch thick kevlar board soaked in some sort of epoxy for rigidity, and some sort of edging to keep down the fraying.
It might have been about 3 years ago when someone was hawking a thicker version at a gun show - somewhere between 1/2 and 3/4 inch thick iirc. I asked about the ability to stop a bullet given the rigidity and possibly being torn out of the holder's hands. He invited me to punch one - even had a set of cottton jersey gloves to "protect" my knuckles. I a in shape only if you admit that round is a shape; just as I'm fit only if you admit that I can get into my clothes (in sizes that might hold two really skinny folks if they got real cozy). Anyhow, I did the proverbial wind-up and let loose. While I did not break it like in a karate demonstration, and I did not send it flying across the room like Chuck Norris's roundhouse side kick might have, I did crack it and twist it so the guy let go with one hand. Not bad for something supposedly "as bullet resistant as" a Level IIA vest, per the hype the guy had printed up.
"The kick of stopping a bullet is no worse than the kick of the gun itself," said Tunis,
While accurate, ^^ it does not describe the actual physics of the torsional and rotational physics of hand-holding this device against roughly 12 foot-pounds concentrated onto less that 1/4 of a square inch.
Vests are not supposed to protect the whole body, just the very most vulnerable parts. And if you get hit while wearing a vest I hear you should expect to get a big bruise at the very least, and that a broken rib is not uncommon. Putting this rigid board up against the outside of your body and hoping for the very best sounds doubtful.
But giving one to the teacher might just be what allows them to survive. The shooter will concentrate on the students and/or be bent over in laughter - giving the teacher time to escape.
The other thing I see as a negative is that this does no good being hung on the wall or tucked under layers of papers and other junk in a desk drawer. Just like the home defense firearm that is anywhere that you have to get up and go to get in order to have it in your hands, when you need it you need it RFN and not "a few seconds" from now.
If they are really interested in "protecting" the teachers, get them outfitted with vests and helmets.
Now the big question - will this be more efficient and cost-effective in protecting teachers (and students) than reducing the likelihood and ease of a shooter entering the school building in the first place? $59,800 buys a fair amount of, for example, hard doors and electronic locks. It also protects 4,000 students (20/class) per class period, as opposed to 200 teachers.
stay safe.