Being a teacher is pretty safe. You might have to deal with some sass from your students, especially if you're working in the inner city, but nothing you can’t handle. Hopefully. According to the Justice Policy Institute, there's a 1 in 2 million chance that you’ll die in school. Those aren't bad odds. Unfortunately, we couldn't find any statistics on the frequencies of injury-from-tacks or getting chalk poisoning, but we assume they're low.
Probably the worst you'll have to deal with is a little aggression, some disobedience, and the evil eye from Larry Contrary. You can always send them to detention, although we recommend not using Dolores Umbridge's methods.