By Susan Gerhard

HUMOR, WE tend to learn the hard way, is subjective. (See also: first date.) I stayed up all night drinking up every scandalous word of Sean Wilsey's wronged adolescence in Oh the Glory of It All, my complete trust in his skater's-eye view of San Francisco society suspending all disbelief as he rolled through evil-stepmom stories, adventures in crab lice, even the game of Monopoly in S.F.'s juvie hall with a Los Angeles Crip. After 400 or so pages, you begin to feel you know a person, which is why I was so shocked when I came to one of the very last paragraphs in the very last chapter, in which he offers a wry assessment of the career of Mike White, who, he says, wrote "a very disturbing movie called Chuck the Buck, and a very funny one called School of Rock." I mean, I thought we were friends. I still love the book; it's just that I can't stand the movie. School of Rock – to my eyes, featuring great talents pandering to the now domesticated Slacker market with a cookie-cutter cast of prepubescent stereotypes – just wasn't funny.

What many people didn't know at the time School of Rock came out was that there actually was a real "school of rock" with an all-too-real rock-burned teacher, Paul Green, whose outsize antics were exponentially more entertaining than (if strangely similar to) the predictable explosions of button-bursting Jack Black. Green wasn't too difficult to find – James Iha tracked him down for Spin in 2002 – but as far as School of Rock, the fiction feature, was concerned, any resemblance to persons living or dead was purely coincidental. This week a documentary called Rock School, by Don Argott, exacts almost as satisfying a revenge on its predecessor as Wilsey does on his stepmom, and both memoir and doc use the very same strategy: they tell the better story.

Already almost famous before he even gets onscreen, Green knows how to play his part for the camera; his sunken eyes read "stoner" and his group pep talks/rants speak some combination of not enough coffee and too much ambition. (My favorite goad: "If you stop working.... I'm gonna kill your family!") On a backyard lawn chair he waxes philosophical, like so many former longhairs of Behind the Music fame, about his tastes and goals (though withheld is the information that he is, actually, a philosophy grad of the University of Pennsylvania). He doesn't let on any awareness that teaching a canon of rock classics like Black Sabbath could or should be comedy. His educational reform (the character in School of Rock is named Dewey, which is also the name of a 19th- and 20th-century educational reformer whose philosophy was called "instrumentalism") emphasizes learning by DIY-ing. Key to the course: eliminate mind-numbing teen pop from the canon and replace it with varieties of disciplining, if archaic, rock, seen in this film as a curriculum that ranges from AC/DC to Zappa and most definitely does not include the unique subgenre "Quaker rap," for which one student is mercilessly mocked.

If your basic kid types – the loner, the rich-spoiled, the talented – populate Green's movie, they're all the more interesting because, as a bonus of the doc genre, they are immediately granted authenticity that paid actors rarely earn. How crazy is it that a 12-year-old can be trained to play the most complicated Zappa and render a flawless "Black Magic Woman"? Crazier still, the tongue-in-cheek warm-up words before the school's Black Sabbath show: "Do you love this song?... Do you love Satan?"

This particular School of Rock is all the more funny – and I mean that in the strange-funny/scary-funny senses – because the parents aren't angry and outraged their children are guitar noodling when they could be polishing their SAT scores; they're the ones eagerly signing them up and egging them on. The mother of the film's star twins, who's seen getting the gel right on one blond nine-year-old's Mohawk and painting "Ozzy" on the other's fingers before a performance, explains that she demands her kids play their instruments as loudly as possible at home, where she can hear them. The only time she draws the line is when one kid desires a pentagram tattoo. Another parent, one who teaches keyboards at the school, looks on while Green transforms his comely daughter from a lover of Sheryl Crow and sometime Quaker rapper to a howler of Zappa.

Does that make you laugh? Green doesn't think it should. Maybe that's why a film that plays his truly odd music-school revolution straight actually leaves us room to enjoy it.

'Rock School' opens Fri/3 at Bay Area theaters. See Movie Clock for show times.