A back-to-school special where no one does homework, “Step Up” partners a delinquent foster kid from the ‘hood with a wealthy dance student at Maryland School for the Arts. He’s pressured to steal Escalades; she’s pressured to apply to Cornell. Tyler is played by Channing Tatum, a former Abercrombie & Fitch model who was a soccer preppie in “She’s the Man.” Buena Vista Pictures hype says he “emerged as a new face to watch in an edgy 2002 Mountain Dew commercial.” Nora is played by Jenna Dewan, a dancer who toured with P. Diddy and Janet Jackson before appearing in “Take the Lead.” Caught vandalizing Nora’s school, Tyler is sentenced to 200 hours of community service, ample time to fall for her before the big show. Writers Duane Adler and Melissa Rosenberg, a Bennington College dance major, fearlessly deploy every cliché in the book for affirming teen self-esteem. Longtime choreographer and first-time director Anne Fletcher, who once danced with Paula Abdul on the Oscars, at least lets us see more Baltimore scenery—including a fruit peddler and his horse-drawn wagon—than “The Break-Up” showed us Chicago. The melting-pot message: jazz dancers—like the ballroom dancers, gymnasts and cheerleaders in recent films—blossom after they’re pollinated with the moves and grooves from the other side of the city. Yo! Old-schoolism of the Old World: hybrids rule, love wins, uplift for all. Score includes “Canon In D” performed by Nuttin But Stringz. Unintended message of over-age casting: juniors and seniors in Baltimore high schools are about 27 years old. With Rachel Griffiths, Heavy D, Mario, Damaine Radcliff, Alyson Stoner, De’Shawn Washington. 98m (Bill Stamets)