INDEPENDENCE, Mo. – During the lunch hour at Three Trails Elementary School, head custodian Alo Key wipes down the tables and then pulls out his guitar.

"You guys are gonna sing with me, right?" he asks the summer school fifth-graders at the Independence school.

The response is bashful at first, but as Key's smooth, soulful voice brings the cafeteria to near-silence, his audience can't help but join in for the chorus.

Ed Sheeran, Justin Bieber, music from the Greatest Showman. Key plays some of the students' favorites, then slides into an R&B mash-up of Sam Cooke and the Drifters. He throws an original song into the mix.

Key, 36, has only been head custodian for a year. He's been singing since childhood.

Growing up, his father "groomed" him and his siblings into being a part of his band, "whether we had a choice or not," Key said with a good-natured laugh. "We'd want to go outside and play, but we'd have band practice."

In high school, Key got his first taste of the music business when he, his older brother and two cousins went on a two-year tour in Europe. They were signed by an Austrian company that had the group singing "techno-pop." It was the late '90s. Key figured the company was going for a Backstreet Boys feel.

In the late 2000s, he began uploading his songs to YouTube. Today, his videos have 1.7 million views.

He has sung in Kansas City's Blue Room. He has sung with Spawnbreezie, another artist from Independence who has made a mark in the music industry. And now he gets to sing for his students.

"They're a good crowd. I haven't been booed yet," Key jokes. He said the students are surprised when they find out he can sing.

"They're like, 'Whoa, Mr. Alo, you sing?' It just kinda tickles me a little," he said.

But Key does more than sing. He's formed relationships with his students and gives them high-fives around the halls. After just one year at Three Trails, he was awarded "Employee of the Year."

"He's just not like a janitor or someone who cleans up your stuff," said fifth-grader Makayla Marshall. "He's also a friend to all of us."

Key, married and the father of five children, is all over the building during the school day, so the students see him often and have been able to connect with him personally, fifth-grade teacher Heather Buckner said.

"He comes to work with a smile on his face and carries that positive attitude throughout the entire day," she said. "We are all about building relationships in the building, and he is one of the key players."