9/11 was truly a horrible day, and should be remembered with reverence to those who lost their lives and sympathy towards their families.
Unfortunately, when it happened, my school did a poor job of explaining it. I was eight, I think, and I didn't quite understand what was going on. The school even tried to cover it up from us, and banned the use of TV's in all classrooms after a couple of teachers let the students watch it. I mean, I guess they didn't want to frighten us, but they never really explained what happened.
Plus, my school today did a very poor job of remembering it. We had about 15 seconds of silence in my first period, but other than that, no other teacher bothered to even mention it. Lack of respect like that just sort of bothers me. =/