The assassination attempt on Ronald Reagan. I was on the school bus home, they dropped a kid off, and her mother came out to tell the driver what happened. March 1981, as I recall ... still in grade school.

I do recall seeing Challenger live in my 8th-grade earth science class, and then walking around the rest of the day totally stunned...even to this day, space-buff that I am, when I hear the radio call "go with throttle-up" during shuttle launches, I get chills in my stomach.