King Corn feels like the most ambitious state fair science project ever -- and, at the same time, I mean that as a compliment, I assure you. Most documentaries, most journalism and most bar-chat could use a shot of the kind of fact-checking, rigorous method and clearly-communicated conclusions you find in a well-tuned science fair exhibit. Two university pals, Curt Ellis and Ian Cheney, take a cross-country road trip; being nerds, they keep track of their meals -- and, being total nerds, run their hair through a spectrogram to see what that says about what they've been eating. It turns out they've been eating mostly corn -- so the two go from Boston, Mass. to Iowa to grow an acre of corn. They have no training in agriculture. They're just curious. When I was a kid, I liked Richard Scarry's Busytown and The Way Things Work. As a grown-up, I read a lot of police procedurals and watch a lot of PBS. It's safe to suggest I may be the target audience for this film. At the same time, there's a heart to King Corn, a warmth and grace to it, and a few good laughs in between the talking heads. We've already had Fast Food Nation (the book), Supersize Me, Fast Food Nation (the movie) and other digressions on the nature of food in America, but King Corn manages to wrap low-key comedy and all-American hokiness around an iron-strong core of story and concept. And yes, there have been a lot of documentaries about food recently; at the same time, last time I checked, everybody eats.

King Corn's methodologies feel complicated, but not confused: Curt and Ian are not using themselves as lab rats at great length; the film's not mocking the good folk of Iowa; Curt and Ian aren't going in with a point to prove, just questions to answer. There's a little earnestness in King Corn -- both Ian and Curtis's great-grandfathers came from the same town in Iowa they go back to grow in. And there's also humor in King Corn, like a goofy slide down a mountain of industrial corn in storage or the use of Fisher-Price farm playsets for stop-motion sequences demonstrating the nature of modern farming.

But there are talking heads in King Corn, and they have plenty to say. Michael Pollan sums up industrial farming's pitfalls when he says "If you stand in a field in Iowa, there's an immense amount of food being grown-- none of it edible." In fast order, Ian and Curtis learn that they're growing an industrial product -- a raw material for making beef, port and sugar syrup. A chance meeting -- at a drive-through -- with a man whose vanity license plate reads 'CORNFED' kicks off a discussion of how cattle eat corn, and why they shouldn't.

King Corn isn't firebrand-angry; no one watching this film is likely to go and heave a Molotov cocktail at a combine after seeing it. But maybe -- just maybe -- anyone who sees it will be charmed a little bit by it's can-do science fair spirit, and thus inspired to think about where their next burger actually came from, or what portion of their tax dollars are subsidizing the mega-sizing of their next soda. That's not bad, for two kids with a dream, a camera and no idea of what they were getting into.