Amyin Muhammad, 14, and Yusef Johnson, 10, were going at it in Camden, N.J.

Amid the fumes of passing buses and the scent of incense curling up from the tables of sidewalk vendors, Amyin, the ninth-grader, had challenged Yusef, the fourth-grader, to a joust in what has become a regular urban street sport: chess.

It also is the main subject at what is known as the Camden Street Academy -- four folding tables with chessboards presided over by Baba Yatahma, academy founder, street vendor and longtime denizen of the corner.

"I've been coming every day during the summer for the last four years," said Amyin as he tried to focus on the board and talk at the same time. "Baba taught me how to move the pieces."

Yusef took Amyin's pawn as Amyin talked.

Slipping his bishop onto the square where the pawn sat, Yusef declared, "I been playing since I was 3 years old."

While the state is spending $175 million to revitalize Camden, Baba Yatahma and other community activists such as Jameel Sadiq -- another academy regular -- are trying to save its young people by promoting chess as a fun alternative to hanging out on street corners.

In Philadelphia, district chief executive Paul G. Vallas also wants to spread chess to all 264 public schools during the next four years.

Nationwide, the teaching benefits of chess have been gaining attention, said Glenn Petersen, publications consultant for the U.S. Chess Federation. In New Jersey, he said, legislation was passed more than a decade ago recommending that chess be taught at the second-grade level.

About 1,400 schools nationwide have teams that are affiliated with the federation, he said -- up from about 800 a decade ago. Chess has become especially popular in New York City, where about 125 schools have clubs and teams.

In Harlem, the first black grandmaster in the world, Maurice Ashley, has been active in organizing chess-education efforts, Petersen said. "The fact is, it is relatively inexpensive, and more and more studies are showing a definite value in not only educational skills but life skills," Petersen said.

He said Newark is planning an outdoor tournament as well as a chess-athon, similar to one that takes place in Asbury Park, N.J., every September.

Chess is gaining in prisons, as well, with inmates at New Jersey State Prison trying to form a federation-sanctioned chess club. In Philadelphia, chess tables sit out in the open at many popular public areas.

In some places, players race the clock in making moves. But the atmosphere is more laid-back in Camden. "It's good entertainment," Amyin said. "But it also increases the brain speed. You can think quicker."

"You learn strategy," agreed Yusef, as a knight took a bishop. "You have to think and plan."

Melvin Atkinson, 42, a chemical specialist, brought son Saladeen, 6, to the academy. "It elevates his mind," Atkinson said. "It gives him discipline, patience and endurance. . . . The whole concept of capturing the king teaches him to make smart moves in life, to think more strategically, to think before an opponent does. You have to have discipline and wait and move and then retaliate."

Besides keeping the boys -- and some older players -- engaged, the games serve up a bit of street theater. "I come out here every day to watch," said Najlaa Muhammad, 20, Amyin's sister. "I'm learning to play -- me and my sister.

"For my brother and his friends, it keeps them off the street," said Muhammad, as her 3-month-old daughter, Makayla, napped in a stroller. "It gives him something to do besides sit around and watch television or get in trouble."