The 15th anniversary of the Sept. 11 tragedies puts America’s major watershed moment at a strange place in time: almost a generation ago.

Our high school seniors have no personal memory the events of Tuesday, Sept. 11, 2001. You’d probably have to be a 19- or 20-year-old to remember what happened that day, when terrorists forced airplanes into the World Trade Center towers, the Pentagon building, and a field in Pennsylvania.