Not about explaining something painfully obvious so much as informing someone about stuff any sentient American adult should know, but jaw-dropping nonetheless:
I took a woman to see War Horse on New Years day. She was a model in New York (way) back in the day, and still looks pretty damn good, even in her early sixties.
She also had a long and successful career as a professional photographer -- magazine covers and awards and such. Her head floats in the clouds, though. Her house is uber cute, if you're into every shade of pastel known to man. She's not exactly stupid and helpless, and yet . . .
As the movie began she asked me when World War I was. I told her, 1914-1918. She then asked who fought whom, and were we involved. I told her. She then asked who won!! I . . . told . . . her.