I can't tell you how much learning happened, but I felt safe.

I just read about the "last ditch effort" method being discussed in Georgetown MA. They are going to teach the idea of throwing books, glue bottles, chairs etc AT THE GUNMAN. I guess in a fight or die situation, anything goes, but come on!
Lock down drills are becoming commonplace in all schools now, what's that saying to our kids?

It pays to be nice to *everyone* if the alternative is tomorrow they come back with a gun.

You are still being lied to. Big time. If you want to find out what really happened at Columbine I suggest you read what the eyewitnesses had to say:

"I always felt very safe when teaching in a juvenile prison."

Would we be better off allowing people with concealed carry licenses to carry in schools?

Of course the best "defense" would be to create an social atmosphere in the school where disturbed outsiders like those at Columbine would be recognized and re-integrated rather than ostracized.

Preparation for the highly unlikely, remote minimal chance etc.

Several states have laws requiring them to keep track of crime by specific category, broken down by those with licenses and everyone else--including mobsters, teachers, police, etc. In other states, they keep track of revocations for cause, and data can be inferred, although details on specifics aren't available.

Samuel Granillo, Columbine High School Shooting …

The Aftermath of Gun-Free School Zones
created by the 1990 Crime Control Act

1776-1990 - 214 years = 7 incidents
1990-2007 - 17 years = 78 incidents

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Non-license holders includes, say, mobsters? I am not being sarcastic, but I am very curious to the exact comparison and methods used. Non-license holders, police, and license holders all work/act in very different circumstances. 'Violent crime' needs to be defined; there is a chicken and egg problem as the current gun situation affects any numbers involved. Finally, I would be really worried about law abiding star citizens with depressed teenage rebellious children, to name just one case. With guns, a mistake is easily fatal. When fighting guns with more guns, more mistakes will be made.

Free High-School papers, essays, and research papers.

"People with carry licenses historically have extremely good records--6-8 times less violent crime than non-license holders, and somewhat better than police."

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They are the most protective of their charges, and the most likely to be aware of a change of routine. And, the first troops on the ground, as it were.