Brian Weiland is with the band.

Exactly which band is highly variable.

Determining the band or for that matter the instrument Mr. Weiland plays is a little like a game of musical Mad Libs. Drums with The Daytrippers, a Beatles cover band. Mandolin with The Flying Elbows strings group. Guitar with Apocalypso, a self-described CalypsoRock band. Hammered dulcimer with the Misfits of Avalon, a traveling Irish-Celtic ensemble.

By day, he’s the general music teacher at the Oak Bluffs School, teaching primarily singing, recorders and guitar. “Really, anything musical is fair game,” he said. “I teach them about music history and about instruments, and about the science of music.”

It’s a far cry from the original path Mr. Weiland, 45, set out on. He was an air traffic controller in the Army before entering the University of Massachusetts as a physics major.

As for music, “It was always the dream, but I had always been told that I should do something more practical,” Mr. Weiland said in an interview last week, standing in the music room of the Oak Bluffs School. Most of the instruments there were Mr. Weiland’s at some point, including his hammered dulcimer and his first guitar, bought with his first Army paycheck. In one corner of the room what looks like a small fort is in fact a recording studio, complete with soundproofing material, which Mr. Weiland built this year for his students. A basket beneath his desk contains copies of a guitar book he compiled for the older kids in the class, featuring songs by Dylan and Guthrie, but also Taylor Swift, Adele and One Direction.

“Music wasn’t really seen as a viable career option,” he continued, the irony of the statement hanging in the air.

He stayed on the physics path for three years, but kept playing music in his spare time. Mr. Weiland met his wife, Jennifer, at university when she saw him play guitar and asked him to teach her the instrument.

“At some point,” he said, “I realized that I could be a really, really miserable physics teacher, or a really, really happy music teacher.” So he switched majors his senior year, effectively becoming a freshman again.

“Oh well,” he said of the change. “That’s what I did — and it’s awesome!”

Throughout college, Mr. Weiland drove tour buses on the Vineyard in the summer, and after receiving his degree but having no music job to go with it, he came back for one more season. When the music teacher at the Oak Bluffs School went on pregnancy leave at the end of the summer, Mr. Weiland stepped in. When the teacher moved off-Island the next year, he applied for the full-time position. That was 15 years ago. On a recent Friday afternoon, Mr. Weiland hauled a keyboard and drum kit through the halls of the school to the front lobby for a strings recital. Daughter Avalon, 11, perched on a stool on the movable platform. Strings and band lessons are part of a different music curriculum, taught by instructors who travel from school to school. But many of the basics are taught in the music room.

For starters, everybody learns to read music. Mr. Weiland is intent on breaking down the musical language barrier, an aim that stems directly from his first months in the University of Massachusetts music program, when, after having auditioned and been accepted as a percussionist, he found himself perplexed by sight reading.

“When you’re a drummer and a boy, nobody ever asks you to read the notes,” he said. “I had to do some serious catch-up.”

In the classroom, third graders take up the inexpensive recorder as their first step down the road to reading music. By fifth grade they are mastering harmonies and polytonal music, practicing as a unit tunes such as Scarborough Fair, which the fourth and fifth grade classes performed last week in their spring concert.

Concerts and performances are a staple of the music program. The school puts on one musical in the fall and in most years does a second show in the spring. Two years ago, the spring musical revue was an all-Beatles lineup. But to fully capture the spirit of the Fab Four, Mr. Weiland knew that only a full rock band backing up the student singers would do. He started making calls.

“And then before I knew it, a couple more really premiere Island musicians were calling me up and saying, Can I be involved?,” he said. “So suddenly I had this world-class band playing for my kids show, and it was brilliant; it was amazing. The kids loved it, the parents loved it, and when it was over, the band kind of looked at each other and went . . . we should keep doing this.”

Enter the Daytrippers. Mr. Weiland intended to play guitar for the band, which consists of Charlie Esposito on bass, Boaz Kirschenbaum on keyboard, Shelagh Hackett on vocals and Eric Johnson and Doug Brush on guitar. Mr. Brush is also a fellow Oak Bluffs School teacher. Initially, Mr. Weiland thought he would be a guitarist, too, but on hearing Mr. Brush play, he promptly ceded the role and took up the drums.

His guitar skills come in handy with Apocalypso, where he accompanies Island drumming maestro Rick Bausman and Mr. Bausman’s son Hudson. Mr. Bausman plays steel drums while Hudson lays down a rock and roll beat against Mr. Weiland’s folksy guitar and vocals.

“Somehow when you mix all of those things together, it works,” Mr. Weiland said. The group was formed, he said, so Hudson, a “phenomenal drummer, not just, ‘look, the kid can drum,’ ” could have a band to play with.

Mr. Weiland’s oldest son, Liam, age 13, is a young drummer himself, and was the spark for the Misfits of Avalon. “The kookiest fun weird [group],” he said. When Liam was eight, he went with his dad to King Richard’s Faire, the largest Renaissance Festival in New England, and was more taken by a drum merchant’s wares than by the jousting. When told he couldn’t stay for the drum circle at the end of the day because of ferry conflicts, Mr. Weiland made a typical parent promise to Liam: next year, they would come back and play the Faire as a real band.

“I’m thinking, okay, he’s eight, he’s going to forget,” Mr. Weiland said. Liam didn’t forget; the Misfits have played ever since, taking the ensemble to RenFests from New Hampshire to Maine. Max Cohen, a friend of Mr. Weiland’s, was part of the original lineup, but the group didn’t actually gain an Avalon until more recently.

Avalon Weiland came to King Richard’s Faire for the first time at age seven, when she watched a minstrel-and-harp duo perform.

“She looked at [the harp] and went, that looks like a cool instrument—it’s pretty, and it’s elegant, and it makes a pretty sound,” Mr. Weiland said. “I take zero encouragement to make musical things happen.”

“She might have just said, oh, that’s a neat thing,” he amended, “And I might have run with it.”

All the Weilands play an instrument or two or several. Jennifer studies violin, while Liam also plays cello and younger brother Aiden, six, plays drums and violin. Still, the family is not as von Trapp as they might appear.

“Sometimes we all get together and play. But as often as not what we’re really doing is sports,” Mr. Weiland said. Liam and Aiden play soccer and baseball, Avalon is a figure skater. “So oftentimes I get home and we rush off [to practice] like any other parent,” he said.

“I believe they should learn to play an instrument, just like I believe every kid in the school should do music,” he said. “[It’s] an important powerful part of our spiritual and holistic being. It’s how we create, it’s how we emote, it’s how we share.

“I just want them to have [music] in their lives in a positive and . . . joyful way,” he said.