Hunched over a chessboard, a poker-faced 10-year-old mocks his adult challenger. "Bring your king," says Solomon Hayes, blowing a giant bubble with his gum. "Bring it on." One move later, the match is over. "Checkmate!" he says. His vanquished opponent, teacher Courtney Welsh, throws up her hands. "Well, at least I beat a six-year-old the other day," she sighs.
At the Harlem Chess Center, which opened four months ago, it is common for grownups to get thrashed by pint-size chess prodigies. In the same tough neighborhood, the Dark Knights team at Mott Hall, a middle school for gifted students, last year...