On 9/11/2001, I was in my French class, listening to my teacher discuss wine, women, and cheese. Mainly cheese. I'm not kidding.
I had been in history class when the first plane hit the tower, but we didn't find out about it until French class. We flipped on the television after the first plane hit the tower, but before the second, so we basically got into a laugh riot. What kind of dumb@$$ pilot can't avoid the World Trade Center? To quote South Park, "It's comin' right for us!"
That quickly changed once the second plane hit. The laughter that permeated the classroom prior to the second shot quickly turned into a sense of "WTF?" - and as the day progressed, and the other two planes hit and the towers collapsed, a new sense of panic fell upon the school - would WE be targeted with our nuclear plants and naval base in the area? It was a solemn day amongst the students, to be sure. I couldn't help but think there were some teachers who took secret enjoyment of watching us hit like that.
I was only 15 then, and while it really wasn't that long ago, it really WAS that long ago. It really held a cloud over the entire high school experience, in its own way.