PARK CITY, Utah - Continuing a doc career that pessimists might say seems devoted to solvable problems that will never be solved, Davis Guggenheim moves from climate change to the crisis of American education.

Waiting for Superman is a moving and effective film whose subject may lack the hot-button box office appeal of the director's An Inconvenient Truth but is at least a crisis practically everyone agrees actually exists.

Guggenheim begins by admitting his own sliver of guilt: Despite an avowed belief in public education, he chose private school for his own kids. A small risk, maybe, but the information lends even more poignancy to the four urban youths he features here -- black and Latino kids from working-class families whose parents don't have the option of private education and must enter them in lotteries for spots in small schools better than the local dropout factories.

The film returns to these families occasionally to humanize what it may fear (unnecessarily, for the most part) to be less engaging: damning statistics about the decline of our schools, theories about the causes of mediocrity (teachers' unions take most of the blame here, though conflicting national, state and local rule books don't help) and profiles of hopeful reformers.

Of the latter, Harlem Children Zone's Geoffrey Canada is both the most inspiring and a consistently entertaining speaker -- not only diagnosing schoolhouse ills but admitting he once believed it would take him two, maybe three years to straighten out the education system single-handedly before he encountered the obstacles that destroyed countless fix-it efforts before his.

The film isn't exhaustive in its critique -- the enormous downside of standardized testing isn't mentioned, for instance, possibly because testing is how we know just how dramatically today's system is failing -- but it cites plenty of blood-boiling practices, like the $65million-a-year Rubber Room in which bad New York teachers draw full salaries while waiting idly for the school district to prove charges of misconduct.

With glossy, commercial-grade photography and a quick pace, Waiting for Superman aims for a wide audience and can't realistically be expected to cover all its material in depth. But many viewers will wish it dug further into the specifics of how great schools succeed and spoke more to concerns that individual success stories are hard to replicate on a nationwide scale. After all, as Guggenheim reminds us, one president after another has claimed to be changing the status quo; it's the specifics where good intentions always seem to stumble.