Laura Drohan bobbed her head and shifted from side to side as she stroked out five chords on her purple, heart-shaped bass, paused, then played the riff again. A few feet behind her, guitarist Geoffrey Perna strummed along, mohawk moving slightly as he bounced his head to the rhythm. People in the crowd nodded to the beat and snapped photographs before the band concluded its blues jam to applause and fruitless shouts of "Encore."

It was the debut performance for Sugar Hi, a nine-member ensemble that played to an overflow crowd of parents, siblings and passersby at Middle C Music in Tenleytown on Wednesday night. The performance marked the end of the store's Rock Band Camp and part of owner Myrna Sislen's efforts to introduce youngsters to music and bring neighborhood residents into the store.

"I want to make it a community place where everyone feels comfortable," she said.

In the past eight days of camp, the nine campers, whose musical experience ranged from several years to nearly none, had learned five songs. They began and ended each day with a blues jam and in between practiced songs including Eric Clapton's "Sunshine of Your Love" and AC/DC's "Back in Black." Amid breaks for chatting and peanut butter and jelly sandwiches, they debated band names, rejecting several possibilities before settling on Sugar Hi.

Counselors Alex Cho, 22, and Charles Williams, 17, said the most difficult part had been teaching the campers to listen to each other as they played. Many campers had taken music lessons before but found playing rock a new experience.

After nearly five years of classical violin, Rose Levy, 11, learned to play the rock violin, an instrument with an electric plug-in on the side.

Laura, 10, had played piano but never rock. She had recently seen the movie "School of Rock," in which a girl plays bass guitar. Deciding that was "kind of neat," she became interested in playing bass and learned on the purple bass from Middle C called the Daisy Rock Girl Guitar.

Other campers had more musical experience.

Bryan Mooney, 12, had played guitar for almost a year in his own band, which he said plays slower rock such as Beatles songs. At camp, he said, he learned to improvise and play solos, which he demonstrated during the blues jam at Wednesday night's performance.

Hannah Ceja, 11, and Becky Koretz, 12, had been playing in their own band, the Bugs, for about a year -- Hannah on guitar, Becky on drums. Both sported green highlights in their shoulder-length hair, though Hannah's parents allowed her to use only spray-on coloring that could be washed out.

Geoffrey, 12, wore the band's other unusual hairdo, a mohawk made from glue and hair gel. Getting it out takes "a lot of showering," he said. He started guitar six months ago, for "the chicks," he said, to the giggles of his bandmates.

The campers said they planned to continue with music, and Sislen said she hoped to host a weekly jam session for the campers and other area youngsters to continue the rock band.

As the crowd cleared and the band members went home, their backdrop, SUGARHI spelled out in colored-in block letters on purple construction paper, remained hanging across a shelf of opera scores, masking part of Middle C's eclectic inventory.

Sislen, 58, began the camp this year.

A classical guitarist, she said she bought the store on a whim two years ago, after learning that the former owner was selling it, in the hopes of keeping it from becoming just another mattress or cell phone store.

With no experience in retail, Sislen sought to find ways to give the store a niche. She hired musicians to teach lessons and compiled a jazz CD with music from local artists.

Near a rack featuring CDs by local musicians, she sells jewelry including red earrings made out of guitar picks with "John Kerry for President" engraved on them.

She said she tries to host performances in the store's small front section as often as possible and sponsors two teams in area youth baseball leagues.

Though she "never aspired to retail," Sislen said, she loves the opportunity to showcase local artists and to bring musicians together. She said parents had approached her after the concert to ask if they could join in jams themselves.

"People making music in this place -- this is really the reason I bought this store," she said.

Laura Drohan, 10, left, plays bass guitar; Madeline Alpert, 11, is on the saxophone; and Rose Levy, 11, the violin. Middle C Music store owner Myrna Sislen wants to introduce children to music and bring residents into the store. Geoffrey Perna, 12, created his mohawk from glue and hair gel. Fortunately, it comes out after "a lot of showering." He started guitar six months ago.