I'm sorry, 'saftey in a classroom'?

Ignoring the obvious typo, it seems like OP is implying that there would be some sort of stampede as the bell rings, leading to some sort of horrifying crush oh my god aaaaaaa… that's all I can come up with as explanation. Seriously, classroom safety? Is this a problem?

The other point, 'you need to get homework assigned', doesn't make much more sense when you consider this: as a teacher, you've got about 45 minutes with your class from bell to bell. (At least that's how they did it where I lived.) You could probably use 30 seconds of that time to say what the homework is.