I work in a school. We had a new alarm installed and finally hooked up two weeks ago. Last week one of the kids, like they do, set it off at the end of morning break.
From this we now know:
1. It's fucking loud - like painfully loud, as in industrial deafness loud.
2. Nothing gets a kid outside quicker than the prospect of a 'free' lesson
3. Play a loud, constant tone down a long corridor and, right before you go deaf, you notice some really interesting interference patterns in the sound.