Honor for America: Losing Significance?

I was walking to my biology class this afternoon when I looked over to the administration building and noticed the American flag being flown at half-staff today. Whenever I see this I imediately think, "What day is it?" After that question is answered I start to wonder, what is significant about today to don this honor?

So, today is 16 October and as far as I am not sure what happened today to warrant a flag at half-staff. This is NOT to disrespect anyone, but I really don't know why. I know at times people will lower the flag in honor of fallen soldiers from their base or post but ASU, why did you lower the flag?

I would not ponder this question so much if I hadn't already seen the flag at half-staff 5 times already this year when I didn't know why. They did lower it on 11 September, but I know why they did that. Why the other days?

This question is only being posed because quite honestly I feel that if this honor is sometimes mis-understood. I just want to know why before it looses the significance and people no longer reflect on WHY the flag is not at full-staff.