Watching Gregg Breinberg effortlessly settle down 60 high-spirited fifth-graders is enough to leave you in awe.
But when he cues his class to open their mouths again, you can't help but be left speechless.
Meet the choir of P.S. 22 from Staten Island, N.Y.
Who knew fifth-graders had so much soul?
"Fortunately, I knew fifth-graders had that much soul," Breinberg said.
Known as "Mr. B" to his students, Breinberg is the first to admit that he's not your typical chorus teacher. At times he acts more like an overgrown fifth-grader than the 35-year-old he is.
As he sees it, his job is to coax students to forget the sheet music and just sing. One of his tactics is to dispense with the usual music class fare.
"That's Coldplay's 'Viva La Vida,'" he said. "No children singing 'Kumbaya' here. ... These kids are so far emotionally beyond that stuff. They need an outlet. These kids, you know, some have been through tough places, some have been through a lot."
About three-quarters of the students at P.S. 22 are eligible for free lunches. Some are struggling at home, Breinberg said. Others are enrolled in special education classes, or are learning English as a second language.
Breinberg said he hopes music gives the kids a chance to overcome whatever barriers they might face.
"You seem to be lost in the song a little bit, closing your eyes and feeling it," 11-year-old student Mariah Baez said. "This just seems to be coming from me, yeah, 'cause first, when I was littler, I was scared about what the people would say. And then now, Mr. Breinberg was like, 'Oh, just feel it.'"
Breinberg said a big part of his work is making his students feel comfortable in their own skins.
"A lot of these kids may be struggling academically, and they may not feel like they are succeeding in other areas," he said. "And they go to this place where they can totally be themselves and be comfortable about being themselves."
That's what happened to Jared Holness, 10. He used to dread speaking in class -- much less singing.
Music Class: 'Eye of the Tiger'
"I was shy," Jared said. "I thought I was gonna be forced to do a solo, so that's why I was like 'Noooo...'"
Which is what makes Jared's story all the more amazing. After singing with the choir for a few months, he did something completely out of character.
"He came to me with this song -- 'Eye of the Tiger' -- and said, 'Mr. B, can we do this song?' I asked him to sing the part to me 'cause I pretended to, I didn't know how the song went," Breinberg said. "And I was like, 'How does that song go? How does it go?'"
The performance was so stirring that another teacher videotaped it. The class posted the video on YouTube. Today, more than half a million people have watched it.
One who saw was Jared's mom, Hope Holness.
"My friend from Chicago e-mailed me, saying, 'You have to see what these kids at some elementary school is doing -- this is why we need music programs,'" Hope Holness said. "And she sends me this link -- and I was like, 'That's my son!'"
Jared's mother had no idea that her once painfully shy son was an Internet sensation. Jared had found his voice.
Is he still shy?
"I can do this," he said. "But I still can't talk to girls."
And it's exactly that innocence, that ability to overcome obstacles, that has drawn more than 4 million people to the P.S. 22 videos online.
The choir sang with Tori Amos in New York and opened for Crowded House at the Fillmore.
Stevie Nicks, formerly of Fleetwood Mac, said their rendition of the group's song "Landslide" brought her to tears. So now they're singing for her June 11 at Madison Square Garden.
"It is humbling," Breinberg said. "It is truly humbling. I went into this job to teach music. ... I mean, I shouldn't be having the opportunities I'm having."
The kids know they are part of something special. But next month, the music they make together will be just a memory. The fifth-graders will graduate, and most will go on to schools that don't have choir class, because so many music programs have been done in by budget cuts.
"It's heartbreaking," Breinberg said. "A lot of schools don't have music programs anymore. It's very upsetting.
"For some of them, [the program] means everything. It really does," he said. "Some of these kids, I truly believe this program will save their lives, 'cause they will go on and they will know they have something they're good at."