If I recall correctly, with a CCW in the PRK you do not need anyone's permission to enter school grounds while carrying. That entering with a gun clause is only for people who want to bring guns on school without having exemption status (police and CCW holders). So technically, I can carry on and off school grounds all I want because I am exempt from the law.
However, I am an employee of the district and I would need to read our personnel policies concerning weapons. I know for the students, they will get expelled for any firearms brought on campus. I have not bothered to check out the personnel policies to see what they say about my employement and having a weapon on campus. I am guessing that it will say I can be fired if I have one on campus. I need to check.
Even if I were able to CCW on campus, I probably would not. Unfortunately there are just too many issues surrounding it and I don't want to be a test case. Second, I don't know how the students would react to it. Yes, we say concealed means concealed, but you couldn't tell anyone about it, period. Not even THR. As soon as someone knows you are carrying on school, it will one way or another become an issue. It opens up too many worms. It might not be right, but that is the way society works. I have enough issues in the classroom and I wouldn't want to deal with 30 immature high school students who know I have a handgun on me. Some would be cool with it, some would be intimidated and withdraw, some would probably want to push my buttons. No thanks.
I might consider having one in my vehicle, but that depends on district policy. It would be much easier for me to keep a firearm in my vehicle and not let anyone know about it than having one concealed on my person all day in class. Again, the key is absolutely no one could know about it. Not a single soul.
I think it would be more effective to just train your students to be fighters and go over escape routes and scenarios in a potential SHTF. Make sure they understand that if a shooter comes on campus and gets into out room, it is on. I tell them that if I take a bullet for them, they better kill the guy. I will do the same for them. There is no time to negotiate or talk someone out of it. Deadly, brutal violence is the key. Of course I tell them our first option is to escape out the window and hop the fence next to my classroom and run. We are on the edge of campus, so we have a good shot of getting the hell out of there.
Sometimes you just have to accept that no matter what happens, it might be your time to go. So if the Lord has my exit plan scheduled for a school day and at school, then that is it. Oh well. The rest of the time, I carry so He might use me to stop someone else from having a early exit. I also accept that He might have me exiting in a hail of bullets and my CCW might not do me a bit of good. That is why I don't worry about it.