Not long after, a nervous Riola was making his Massey Hall debut in the school’s annual, sold-out Christmas concert in Toronto.

“It was daunting,” he said.

“I was still a soprano and was very small for my age. When you step on stage, the lights are so bright and the crowd looks huge. It’s a big experience for a small kid.

“But I started to relax once I got into the music. It felt like I was a part of a real concert.”

As he took the stage earlier this month for the choir’s 80th Massey Hall Christmas concert, Riola had grown from an unsure 12-year-old soprano into a strong and melodic baritone. In a choir of 160-plus students, his voice resonated above the crowd.

The students, aged eight to 18 with vocal ranges from soprano to baritone, performed part one (which recounts the birth of Christ) from Handel’s 18th-century oratorio Messiah. For many of the junior students, it was their first time on stage. For a graduating student like Riola, it was a bittersweet night knowing this would be his final performance as a St. Michael’s student.

“To be honest, it is a bit emotional,” said Riola, 17, who has been at St. Michael’s since Grade 7. “But the nervousness and the excitement is there like every other year. If anything, it was elevated because I wanted to give the best possible performance.”

Every year, choir director Peter Mahon bids farewell to some of his student proteges. But he says it is not an end but a new chapter in their life.

“I am very happy for the guys when I see them graduate and go on to do lots of incredible things,” Mahon said. “Especially if they stay in music, then my relationship with them will probably continue.”

In addition to his commitment to St. Michael’s, Mahon is active in Toronto’s music community. He sings in several choirs and is the artistic director of the Tallis Choir. But he seems to take special pride in his work at the choir school.

The students are all talented vocalists. They are also teenage boys. On a chilly morning they shuffle into a drafty rehearsal room. They talk video games and skateboarding. One preteen scrolls through Instagram on his iPhone and another climbs onto his chair, turning around to speak to a boy behind him.

The shenanigans stop the second Mahon enters the room.

“No more chatter gentlemen, take out your books,” he says calmly.

He sets down his coffee on the piano and faces the choir. “Stand. Now, ‘Hallelujah’ from the top.”

Photographers and videographers hover, snapping photos and zooming in on the singers. The boys appear indifferent to the activity. According to Riola, you just get used to it after a while.

He has come a long way from the day of his audition when he learned that he could sing.

“It just sort of came out,” he said, laughing. “I had taken piano lessons for years so I had a background in music. But I did not know I could sing well.”

Despite an intensive musical education, only a handful of choir school graduates pursue music as their career. Some, such as Canadian jazz singer Matt Dusk and the late actor/singer Michael Burgess, who starred in the stage production of Les Miserables, find success. But most students find other professions.

“Almost all of the boys go on to university,” said Stephen Handrigan, the school’s director. “Many of them become successful doctors, lawyers, teachers and businessmen. It is the musical experience they share here that binds them together in a brotherhood.”

Riola does not plan to pursue music professionally, but like many choir school grads he will always sing. He is considering joining the alumni choir, which often performs with the student choir at major events.

“I don’t want music to leave my life completely,” said Riola. “Since I came here, I’ve practised week in and week out. I am not going to forget everything I have learned here. Music is a part of me and it’s going to stay with me for the rest of my life.”

The experiences the students share — from performing at their first Christmas concert to weekend rehearsals to playing basketball at recess — creates a deep bond.

“We’re all best friends,” he said. “We spend so much time together. Not just at school but after school and at weekend practices. We aren’t forced to bond, we all just click.”