Surprised that your safety/fire marshal would approve this. What about fumes? Is it vented? That would be another HUGE concern if not - although on closer look looks like there's a hose/vent coming from the bottom. It's not the first time that I've seen that but it's never the best scenario...Would also tape off the floor area & threaten severe consequences for ANY student that crosses the line. Good Luck!
One of my classrooms has a kiln in the corner too. I educate the kids about how hot a kiln gets, and instruct them to never touch it. They're actually pretty scared of it!
You definitely need some venting and I would not fire it while there are kids in the room. What if they opened it while it was firing? Danger. I don't think it is a fire hazard in that location, but I do think you need a proper ventilation system. Talk to your principal maybe about an alternate location for it.
We do have venting. It's coming out from the side of the kiln. Not sure if you can tell, but I have it pretty well blocked. In order for a student to approach the kiln, they have to move a cart or table. The carts are pretty heavy, so they couldn't move them on accident. I don't know how I could possibly get it fired without doing it while the kids are there. At a previous system I had a kiln with a timer on it, which would absolutely be the best option. I also put signs on the table and cart, which say STOP, do not touch. For the most part, the kids haven't wanted to touch the kiln, just the clay projects. It definitely makes me nervous, though.
When I had this situation, I only fired overnight. A colleague's daughter bumped into her kiln after school resulting in third degree burns. You just shouldn't chance it. There's always that one who doesn't listen. My electrical outlet caught on fire one night! Now I have a room for the kiln (and only allowed to fire when I'm present)!