The arc is now as predictable as that of the most prefabricated Hollywood blockbuster. An untraditional or unusual activity sparks the interest of young kids, often those from disadvantaged backgrounds and in troubled schools. It gives them a growing sense of self-esteem and accomplishment and usually leads to some uplifting triumph in the end. But the story isn’t a fictional one, except by extension, of course–when it may be turned into a docudrama. In essence you can see it in a sports tale like “Hoosiers,” but nowadays it seems to pop up most frequently in the faddish form of the feature documentary. It was certainly to be found in “Small Wonders,” the little-seen story of kids learning to play violin in inner-city New York campuses that was later turned into “Music of the Heart.” But it was really the success of “Spellbound” that has led to an explosion of movies with similar themes. So recently we had “Rock School,” and now we get “Mad Hot Ballroom,” in which the activity brought into the classroom to teach discipline, mutual respect and consideration for others is–you guessed it–ballroom dancing.

Marilyn Agrelo’s picture follows the students at several New York City schools as they learn their steps and form into teams to dance in a citywide competition. There’s PS 112 in Bensonhurst, where the principal seems less interested in winning prizes than helping her kids learn etiquette. And PS 115 (Washington Heights), where the class is composed mostly of the children of immigrants from the Dominican Republic and teacher Rodney Lopez demands self-control as well as talent. And PS 150 (Tribeca), where smooth-as-silk instructor Alex Tchassov and quick-to-cry teacher Allison Sheniak lead a diverse group of kids toward the finals. The teachers and students all make pleasant company, and some who are given a bit of extra attention (Sheniak, who shares a poignant last-act reflection with the audience, or student Tara Devon Gallagher, an intense, bespectacled girl who works hard at home on her steps and hopes for a career in entertainment) make sharp impressions. There are also occasional flashes of insight in the conversations the camera records among the various groups of students; and one can’t help but enjoy watching the more colorful or unusual-looking kids struggling to master the dances with partners who sometimes tower over them. (The extensive footage given over to the various stages of the competition, on the other hand, gets repetitive, helping to explain how at nearly two hours the movie seems overextended.)

But ultimately “Ballroom” is too scattershot an affair, offering surprisingly little depth in its coverage of either students or teachers. Quite simply, we don’t get to know any of them fully enough to establish a genuine emotional bond with them. Near the close, for example, one of the teachers extols the effect of the class on one of the dancers, a troubled kid whose disciplinary problems disappeared as the year progressed. It’s a good story, but we don’t see it; we’re merely told about it after the fact. Unfortunately, that’s pretty much par for the course here. And one doesn’t even want to inquire whether dance classes are really the best way of expending tight school budgets.

“Mad Hot Ballroom” is certainly a nice picture, a cannily-designed crowd-pleaser that mixes cute kids and uplifting dedication. But by now the territory it covers has become pretty familiar, and a movie like this needs greater flair and incisiveness to stand out from a growing crowd.