I was in Junior year, American History.  A kid ran into my room and said that a plane hit the WTC (The first plane) and my teacher flipped on the TV.  My teacher said that we could continue watching after his lecture.   
I ran to my next class and told that teacher what happend and that I needed to turn on the TV.  Right as I turned it on, I saw the second plane hit.  From their, I didnt stop watching unless I was switching class rooms.   
After I found out that a plane went down in Pennsylvania, which is where I am from and where the majority of my family still lives, I called my mom to make sure my grandpa who was flying to Florida was OK.  Luckily, he was already stuck in Atlanta, which is where he had to stay for a week.   
Sad fucking day, and I will never forget.  I like to compare this to the day JFK was assasinated.  Ask your parents where they were, and I am sure they can tell you exactly what they were doing. 
-Marc