One sad fact I learned about adolescent suicide (12 to 18 years of age) is that it's seasonal. It picks up during the school year and drops precipitously during summer and winter vacations.
Being in school has a profound impact on whether or not a child wants to kill themselves.
http://basilhalperin.com/essays/school-and-teen-suicide.html
I wasn't suicidal when I was in high school, but I absolutely understand people's depression around the school year.
I actually don't hate school as much as an adult, but I really did view school like a prison when I was a teenager. I didn't like homework, I didn't like most of my teachers, I liked learning but due to the fact that schools have to go at a pace slow enough for the dumbest person they want to pass, I would get very bored during class, and so high school in general was existentially dreadful every day. Even when I got home, I would dread the fact that in about ~15 hours, I would have to go back to school again.
It didn't help that there was a dread with grades in general; I wasn't abused or anything, and I think my parents in general were pretty ok at parenting, but as report card season came nearer and nearer, I would get more and more depressed, because when I would inevitably get middling-to-bad grades, I would get a lecture and/or grounded by my parents. This meant no computer, no games, I wasn't allowed to hang out with my friends, and they hoped that it would force me to study more. It's not dumb logic, but it just didn't work. I would just be sad and angry and still wouldn't do the homework.
No doubt a large chunk of this was just hormonal, but I really think that the typical American school system is not a good fit for a lot of people, myself included. I don't think anyone has ever seriously called me stupid, but I would be in camp that endlessly frustrated teachers: I would do well on the tests, I would do well on the AP exams, no one disputed that I understood the course material well enough, but I just didn't care enough to do the homework so they would be forced to give me bad grades. I don't blame the teachers for this at all, they're just doing their jobs.
Despite being in AP classes and having skipped two grades in math, I was seriously considering dropping out of high school and just trying for the GED so I wouldn't have to go anymore, and I probably would have done that if I didn't think that my parents would freak out.
I didn't want to kill myself, but very few things brought me more joy in my life than knowing I wouldn't ever have to go back to high school again. I know a lot of people say that these are the best times of their lives, and power to them for that, but they were decidedly not for me.