The long and short of it is In this day and age bringing ANY open firearm or even a replica into a school without some prior discussion or plan is simply fookling STUPID. The teacher was 100% in the wrong here.
Not to get too philosophical, but i think there's different kinds of "wrong" .
Here's an analogy:
Stealing is wrong. As a moral principle, stealing is wrong.
So if stealing is morally wrong, then you should be able to leave your stuff around and trust that it will not get stolen. That is, in a perfect moral world, you should be able to leave your stuff unattended and not worry about theft.
In that sense, the person who leaves their car unlocked in a shady neighbourhood has not done anything morally wrong. They are not the one doing something wrong, the person who steals is the one who is wrong, yes?
But in a different sense, a practical sense rather than a moral sense, we all know that in a shady neighbourhood a smart person will lock their doors, and if you fail to lock up, you will be doing something wrong in the practical sense. Right?
And that distinction needs to be made here, i think.
The teacher bringing the inoperative vintage gun to school for a history lesson, that was 100% practically wrong, because we live in an age today where crazy sheltered gun-phobics are in charge, and a smart person would have known those crazies would lose their minds at the sight of an inoperative vintage gun in a school. So on a practical level, yes, the teacher should have known better.
But on a moral level, it's important to maintain that the history teacher is 0% wrong. There is absolutely nothing wrong, on a moral level, with bringing an inoperative vintage rifle to school to teach a history lesson. What moral principle does that break? None. In fact, with a motivation of giving kids a better education, the act was actually morally commendable.
And i think it's important that we make that distinction, because there's plenty of anti's today who would argue that any and all guns are inherently immoral, and that bringing that gun to school was not just practically wrong, but morally wrong as well, and we can't let that kind of idiocy stand without challenge.