As Jerry Chu's fifth-grade music class pounded and blew out the last notes of the jaunty Jamaican folk song "Mary Ann" on Tuesday morning, the veteran teacher suddenly looked askance. Something was missing.

"That sounds good, but you know what, let's get some maracas in there," Chu decided. "Chris, get the maracas out and let's do that again."

Chris, one of two dozen fifth graders crammed into the Kenny Elementary School's basement music room, quickly complied and the fledgling musicians headed towards equatorial waters once again.

"Percussionists, you're going to have to get these notes down better," Chu warned mid-song. "When we start practicing outside, it's going to be harder."

It's been a long time since Chu, the music teacher at the Kenny School near Adams Corner, and his pupils played al fresco in the playground along Delmont Street. But, someday soon, they'll be out there, serenading neighbors in a sneak preview of their big coming out-party this June. You see, this year - for the first time ever - the Kenny School's taking their sounds to the street.

Okay, to the avenue.

The newly-formed, 75-member marching band, under Chu's direction, will step off in its inaugural Dorchester Day parade on June 5, the only such elementary school troupe in the city.

"I have to give Mr. Chu credit for the idea," says Suzanne Federspiel, principal of the 280-student elementary school. "We have had a VH-1 grant that gave us the instruments and we've had it for the last few years. But, (the marching band) was his concept."

According to Chu, a New York native who has taught music at the Kenny for the last decade, the cable network's one-time grant flushed $35,000 into his music department to buy high-quality instruments, which students practice with at school and on their own time, if they win permission from Chu to bring the instruments home.

"They have to get through two lessons first. That's my rule," Chu says.

"It really helps to build responsibility," adds Federspeil. "The students learn that if they don't practice at home, then their friends will get better than them. They all want to play now. There's even a waiting list for the band."

Chu says that the marching band presently includes about 60 students, with another 15 expected to make up the band's color guard. Josephine Spencer, a longtime Cedar Grove resident and volunteer with Generations, Incorporated - a senior citizen organization that helps with literacy and math programs at the Kenny both during and after school hours - has stepped forward to sew the band's flags. Spencer has become one of the Kenny school's most outspoken local boosters, praising Chu, Federspeil and other faculty with bringing a new energy to the Oakton Ave. schoolhouse.

"I want to see the Kenny become known for what they are: an excellent school. The principal has been very cooperative with us.

"I'd like to see the Kenny come up to speed in the neighborhood," says Spencer, who has begun reaching out to potential sponsors to help the fledgling band pay for sneakers, hats and uniforms in time for the parade.

"I'm hoping that the community really gets behind them," Spencer says. "It gives the kids a sense of pride in the school. It gives them great team spirit and it gives them a real sense of pride in the neighborhood, too. It serves a lot of purposes."

Federspiel says that the majority of the elementary school's student body are Dorchester residents. Many are also Haitian-American, as the school is one of two "magnet" schools in the city for Haitian children who are enrolled in English immersion programs.

Next year, she says, the school will expand to include a K-1 kindergarten program for four-year-olds. Presently, the school serves grades K-5.

The school also offers after-school French classes for students, a program funded by the French Library, a Back Bay organization. The three classes are completely filled each day, according to Federspiel, who says, "We're constantly looking for ways to maximize our strengths."

Chu is clearly one of the Kenny's great strengths. Aided by interns from Berklee College of Music, Chu instructs five classes a day. Beginning in grade three, each student gets to pick an instrument and starts an arduous instruction regimen supervised by Chu and his helpers.

"I think they really enjoy coming to school more because of this program. I definitely see a lot more happy faces," says Chu, himself a graduate of Eastern Nazarene College's music education program.

Benjamin Lynn, a 10-year-old fifth grader from Savin Hill Avenue, agrees. The novice trumpet player says he and his classmates can't wait to make the three-mile trek up Dorchester Avenue later this spring.

"My hands might get a little sore, that's all," says Lynn.

The band still has a lot of practice ahead of them before they're ready for their Dot Day debut. Once they step off, though, Chu says he'll be excited to see the reaction of Dorchester to the city's one-and-only elementary school marching band.

"I think it's going to get a lot of notice," Chu says.