When the first plane crashed into the World Trade Center on Sept. 11, 2001, almost a decade ago I was in morning study hall at my high school. It was my senior year.
Ask your average American where they were when they first became aware of the 9/11 terrorist attack, and most that where old enough to remember it will be able to tell you.
Likewise, I believe that most Americans will be able to tell you where they were when they found out Osama bin Laden was killed, as happened on May 1, 2011. I was having a BBQ in my backyard with family and friends when someone received a text message with the news.
Interesting question: I wonder how many people heard about it via social media instead of through any traditional news source? I suspect its a majority.