Teenage and older children in particular should see this film. If the younger teens have nightmares, comfort them. But young Americans need to know the nature of whom we are fighting. If they are attending a typical American high school or college, they probably don't know.
go and see "United 93," to see why some Americans still take "Home of the brave" seriously; and to see why we have to win this war more than any since World War II. That's how bad our enemy is. You have an unfortunately rare chance to see that enemy at work when you see what happened to everyone who boarded United Airlines Flight 93 that left Newark on September 11, 2001.
Then go and read this collection of excerpts of essays/articles/posts on the film: "Flight 93: Remembering Heroes."