Oh, but it was true.
From the panel of windows in our classroom facing the street, a large plume of smoke was visible in the very far distance. The entire class congregated at the windows, stupefied. Our teacher told us to get away from the windows, closed the blinds, and turned on the TV, which verified our worst nightmare. The Pentagon had been attacked.

I called my parents from the girls bathroom. With their offices right off of Pennsylvania Avenue, I was seriously worried for my parents and desperate for them to have escaped the aftermath of the attack. Thankfully, my parents were fine. We discussed transportation; to avoid the other nightmare that was going to be taking the Metro home, my mother picked up my father and me.
In what seemed like a few short minutes--or maybe it was an hour? Time seemed to stop for a while--more parents swarmed into my school's tiny parking lot and wraparound driveway to pick up their students. At that point, no one knew if a similar attack was planned for WMATA; no one wants to be trapped underground* during a terrorist attack, that's for sure. Once we arrived home, all of us watched the news--perturbed, shaken, mournful--well into the night and the entire week thereafter.
Of all those who perished in the attack on the Pentagon, one in particular was close to my family: my father's childhood friend, C.G. The destruction to the wing of the Pentagon where C.G. worked was so severe that his remains could only be identified through dental records and hair samples.

What I learned on September 11, 2001 was that, despite our efforts, very few things are fully within our control. People can either accept and embrace that fact, or live out their lives in fear. Living in fear isn't living at all, and part of me refuses to "let the terrorists win" (omg how many times did people say that in the months following 9/11?!) by doing that. I always try to be aware of my surroundings though, and don't trust easily--never did. "Cautiously fearless" is a good motto for how I felt post-9/11. I try to keep that feeling up today.
*From Inglourious Basterds:
Lt. Aldo Raine: You didn't say the g*ddamn rendezvous was in a
f*cking basement!
Lt. Archie Hicox: I didn't know.
Lt. Aldo Raine: You said it was in a tavern!
Lt. Archie Hicox: It is a tavern.
Lt. Aldo Raine: Yeah, in a basement. You know, fightin' in a basement offers a lot of difficulties. Number one being, you're fightin' in a basement!