That truth, recognised by anyone who has spent even a few hours in, say, a KIPP charter school, is an inconvenient one to the teachers' unions, which the film rightly identifies as a big chunk of kryptonite standing in the way of a dramatic rescue for the children of America.

ECONOMIST: Education in America

He had just watched as debris came down on top of his truck, on its way to a rescue.

CNN: Day turns to night at ground zero

As the outside world waited to learn what was unfolding inside that bunker, rescue teams found a way to see inside.

CNN: Inside the bunker: From storm shelter to boy's prison