Mr. Aaron, a wiry, professional musician with disheveled hair and a disarming smile, tried to pull a fast one on his young students the other day.

He strummed his acoustic guitar in front of a class of about 20 kids. He sang a song, one we all know, called “Wheels on the Bus.” He played it straight at first, singing to the children – a combo of babies and others a few years older – that the wheels on the bus “go round and round.” And then he sang that the wipers on that same bus go “swish, swish, swish.”

Then, oddly, he claimed the driver on that bus “says quack.”

“Quack, quack, quack,” if you’re scoring at home.

Mr. Aaron paused for a second, his wide eyes widening, scanning the class, waiting, hoping, and it didn’t take long for the kids to react. At least those old enough to have understood that they were being conned. Tested, really. They waved their hands, fidgeted in their spots on the carpeted-floor and, in unison, yelled “Nooooo,” with the innocence of a kitten.

They knew what the driver really had said. Always says. “Move on back,” a few countered, reminding their suddenly absent-minded teacher. After everyone had left the Rattlebox Studio on Thorndike Street, Mr. Aaron explained his strategy.

He had gauged the level of focus in his class. Attention spans must be taken into consideration.

“It’s to see if they’re not paying attention,” said Mr. Aaron, known as Aaron Jones to adults, explaining his staged gaffe. “And sometimes you see that they’re not listening, but these ones were sharp. They paid attention.”

It’s tough not to, because Mr. Aaron, 33, leaves the children with little choice. No choice, really. Not when the kids see a smile the size of a slice of cantaloupe, belonging to a teacher who, everyone insists, remembers his students’ names after just one class.

“Not always, but often,” Mr. Aaron admitted after class. “It’s been really important developmentally for kids to hear their names, so that is something I have practiced hugely. I don’t know the parents’ names, but I know the kids’ names.”

He’s Mr. Rogers and the Pied Piper rolled into one, jamming on different instruments, singing, inspiring, educating, moving and, of course, smiling.

He started singing at 10 a.m. sharp, then sparked conversation and asked questions and then sang some more. The kids danced and moved around a lot, some cooperating more than others. One little boy in a red sweatsuit had time for exercise, zipping around the classroom in separate bursts of energy, forever trailed by his aunt.

The one-hour session at the Concord Community Arts Center revealed the many sides to Mr. Aaron’s career, the separate paths he’s been introducing to children since moving to Concord from New York City five years ago with his wife, Anna. They have two kids, another on the way.

And as in life, Mr. Aaron knows he must improvise to make things work. Asked before class, while twisting together his clarinet saxophone, if he had prepared a set list, Mr. Aaron said: “I have a plan, but I have to be ready to adapt, so nothing is rigid. Change is the only constant.”

That’s true in the music field as well. Before he became Mr. Aaron, he was Aaron Jones. He grew up in Atlanta and settled in New York City for 10 years, attending graduate school at New York University, teaching music classes and playing gigs.

In 2013 he made a late-night appearance on David Letterman’s show – “Didn’t get to meet him, but I got to shake his hand.” – while touring with Luscious Jackson, an indie rock band that built a nice fan base through the 1990s and garnered great reviews from major publications.

He’s been commissioned to write scores for college productions, including at UMass Amherst and James Madison University. He played for adults in New York City clubs, and he learned Kindie (get it?) music with a band called Karen K and the Jitterbugs, which inspired him to pursue a very specialized style of music.

He and Anna, whom he met at NYU, moved to Concord 4½ years ago, choosing to raise their family near Anna’s parents, who live in Hopkinton. Around here, Mr. Aaron’s band has played at Red River Theatres, Flipz Gymnastics, local farmers markets, yoga centers, even the Capitol Center for the Arts.

His Rattlebox Studio is filled with song and dance. His class features two large, rectangular rugs, connected side by side, each displaying a print of a large guitar. That’s where the kids sat, and that’s where the action took place, the focus of Mr. Aaron’s attention as he strummed those chords, sang those songs, much of it his own stuff.

His hair these days still has a mind of its own, but it’s much shorter and not as red as the hair you’ll notice on a video showing Mr. Aaron on Letterman’s stage seven years ago, strumming in the background. There, his hair bounces and the band rocks, playing a song called “Show Us What You Got,” with a leather-clad front-woman and a hard-driving, metal beat.

He’s done a 180 since, producing a smorgasbord of sights and sounds for children, most of whom have not started grade school yet. He got a taste of this genre while playing with Karen Kalafatas of Karen K and the Jitterburgs in New York City.

“I played with her bands doing kids music concerts and that was sort of my formative kids’ music experience,” Mr. Aaron said.

His family was growing. He grew tired of city life. He and his wife moved here to be closer to her family, and now he runs the studio while the couple waits for their third child.

Registration for the classes happened near the door, with Mr. Aaron personally signing in the children. Then, shoes off, before the students sat and the adults lined the periphery, surrounding this bundle of energy and anticipation. Mr. Aaron went on at 10 a.m. sharp, standing in front of four huge windows that framed the South End.

The place was packed. Mothers, fathers, grandparents, aunts, all there to see Mr. Aaron cast his unique spell over his audience, energizing them to dance, stretch, sing, wonder.

Michael Davis of Hillsborough was there with his daughter, Kimberly Cortino, and his 2-year-old granddaughter, Marley. She was shy and wore black glasses, and her mother said her daughter was hard of hearing.

“We keep coming back every week because she loves it,” Cortino said. “She does a lot of sign language, so (Mr. Aaron ) has even taken the time to learn some sign language for her.”

Nearby stood Davis, a landscaper, and a big one, who wore a black Harley Davidson T-shirt, blue jeans and a long goatee. His edgy aura, however, melted away into a smile for his granddaughter, who was held by Cortino.

“First time I’ve been here,” Davis told me. “I thought it was cool. She loves music.”

They heard Mr. Aaron sing “All My Friends are Giants” and “The La-La Song,” watched him lead the class in a kangaroo hop, shook and moved to his lightning-fast guitar chords and staccato bursts from his clarinet saxophone.

“All I know about is music,” Mr. Aaron said afterward. “Just the experience of doing this and now having my own kids, I stay patient and I try to stay on their wavelength and pay attention to what’s going on. Be ready to adapt and bail, maybe end a song early.”

Or not. On this day, this class was listening to the words, so they knew.

Bus drivers don’t quack. u