Inside the Blues Alley nightclub in Georgetown, Dizzy Gillespie is playing a trumpet whose bell juts up at an improbable angle. As his cheeks balloon with air, he makes that twisted piece of brass sing and moan and the audience erupts into applause and laughter.

Cocktail glasses tinkle against melting ice in the darkness of the nightclub while cigarette smoke rises to the ceiling, wafting through the colored floodlights that bathe Gillespie's band in warmth.

Through it all, few notice the three young men standing along the back wall, but Gillespie can see that they are mesmerized by the master's be-bop beat, and so he mixes up his show just for them.

"Oooh, papa do," Gillespie breaks out into a scat song, waving his horn at the boys on the back wall. The bass player pounds out a driving beat, the drummer adds accents of his own, and then the piano man and sax player hop aboard for a wild, sweet ride into the realm of improvisation.

"This is some very moving stuff," said Dennis Jeter, 16, a student at the Duke Ellington School for the Arts, who plays trumpet. "If we could incorporate some of this into our own thing, we'd be great."

He and two other students are leaning on the wall, sipping cranberry juice, savoring this exciting thing called jazz. A few days earlier, Gillespie and the band were visiting the school when his sax player, Sayyd Abdul Al-Khabyyr, asked a group of 60 students how many had not heard of Dizzy Gillespie.

"About 10 students raised their hand, but I could tell there were others who were too shy to admit it," Sayyd recalled during an intermission. So the school offered to sponsor three music students for a night of Diz.

"This is funky music, jammin' jazz," said an ecstatic Sean Gardner, 16, another student who plays French horn and baritone horn. "It's awesome. It gets you up, and takes your mind off of Michael Jackson and Prince."

John Chandler, 17, a high school bass player, agreed: "This band is so tough they can stop the music -- and still keep the beat alive."

The three young men say they want to form a jazz band at the Ellington school. And watching the audience of grown-ups swoon over Gillespie's tunes makes them eager to get started.

During a break in the action, Gillespie walks over to them and signs autographs. "So you'll play trumpet, eh?" he said to one of them with a smile.

When asked how old he was when he first picked up a horn, Gillespie cracked, "Fifteen minutes."

Actually, he was 14. That's when he was known as John Burkes Gillespie of Cheraw, S.C. Perhaps the reason he likes younger musicians and spends so much time visiting high schools around the country is because they remind him of himself.

Listen to Gillespie's childhood trumpet teacher, Philmore (Shorty) Hall, a Fairfax County resident who died a few years ago:

"Hell, I thought Dizzy was never going to be much of a trumpet player," Hall said during an interview in 1981. "Diz used to be into devilment all the time. Every time I turned around I had to go see his school principal. I remember one time he climbed in the girls' dormitory. Sometimes he'd be shut out of the cafeteria as punishment for five days a week."

But when you listen to Sayyd, it is clear that Gillespie has more than the past on his mind. He's thinking about the future, too.

"Many of our colleagues are convinced that there is a conspiracy in this country to change jazz into something that it is not," Sayyd said. "People can be made to like or dislike anything based on what the media says about it. So when we have youngsters come in here to see with their eyes and hear with their ears the master -- in person -- they can go forward with the truth of what jazz is and they cannot be duped."

After the show, the three high schoolers be-bop into the night, planning a practice jazz jam session of their own, testimony that this original American art form is likely to be around for generations to come.