As far as I know, this is the first year that Paul has learned anything at school about the attack, and while Ben and I have told him what happened, we haven't shown him any photographs or videos. So I was glad that first visual depictions he was exposed to came in the form of an inspirational video which the Seventh grade Sacred Studies teacher shared with his class. It's called "The Man in the Red Bandanna" and it tells how Welles Crowther, who worked at the World Trade Center, helped twelve people out of the burning floors of the South Tower before losing his life when it collapsed.
The video effectively uses pictures of the burning buildings with audio background to convey the horror in a way that impressed my tender twelve-year-old without freaking him out. There were no falling bodies, no screaming sirens, but rather a sensitive depiction of the terror with the emphasis always on the good that Mr. Crowther chose to bring to the scene. It was an excellent introduction to a difficult topic for my sweet still-little boy.
If you'd like to see it, go to this video on YouTube. It's thirteen minutes well-spent.