The six jazz musicians were really cooking, playing like seasoned performers. But these guys are not professionals - they're teenagers from LaGuardia High School of Music & Art and Performing Arts in Manhattan, and they commanded the stage last week at one of the largest jazz conferences in the world.

More than 400 people crowded into a large space at the Hilton Hotel, site of the International Association for Jazz Education gathering, to see and hear the kids, known as the LaGuardia Arts Jazz Sextet.

The band comprises Travis Antoine, 16, on trumpet; Francis Benitez, 17, on drums; Matt Berman, 15, on alto sax; Luis Gomez, 17, on piano; Michael Sacks, 17, on bass, and Alex Segal, 17, on tenor saxophone.

"We were nervous, but when we got up there to do it, it was great," said Segal after the show. "It was beyond what we usually do."

Flanking the kids onstage was none other than veteran jazzman Bobby Watson, alto saxophonist extraordinaire.

"I'm always encouraged when I see young people their age who are deeply committed to jazz," Watson said later. "This is something special."

Watson prepped the teens through a program offered by the Thelonious Monk Institute of Jazz, a nonprofit group that gets professional musicians into public schools across the country.

J.B. Dyas, vice president of education at the Monk Institute, said groups like LaGuardia are the ones to watch.

"They are the cream of the crop," said Dyas. "These are the ones you'll see at jazz festivals in the next decade, the ones whose CDs you'll be buying."

"It's a joy to teach these kids," said Kevin Blancq, jazz-band director at LaGuardia. "They are so motivated and exemplary, they teach themselves."

After months of rigorous rehearsing, the teens were revved up for the show. Before they went onstage, Blancq asked them, "How many of you really slept last night?" Of the six players, one tentatively raised his hand. "They're running on adrenaline," said Blancq.

After the first number, Watson told the audience, "Look at these kids playing without music - it's wonderful. Every mistake they make today, they will never forget."

Benitez didn't mind improvising without sheet music. "They are really tough on us - but that's cool, we need it," he said.

Performing with a jazz great like Watson was a bit intimidating, said Berman.

"At first we were nervous, but Mr. Watson got us joking around," he said.

"I messed with them and let them know I like to have fun," said Watson. "But I can hear their potential, what they can become. I try to get more out of them."

It was a first for Sacks to introduce each musician. "It was a rush to talk directly to the audience," he said. "All eyes were on me. It was thrilling, and I loved it."