For the kids in Columbine it was because they weren't popular or jocks and they dressed differently from others. As well as what is happening in the school that creates these separations of students. In conclusion I go by a belief that school is separated into two parts, the first being social and the second, academic. Anyone can tell you school is hard and difficult. But it takes a really mature person to say school is hard as well as fun.
Life is hard, but that's what makes life so challenging.