Here’s one key to the success of the Joyous Quintet, the group of Long Island kids who will play their brand of classical music on the new hit variety show “Little Big Shots” at 8 p.m. on Sunday, April 3 on NBC.

They’re cool.

Brendon Lau, 11, a sixth-grader from Williston Park, plays the bass while wearing sunglasses. Mickayla Jia, 9, of Jericho, might be wearing a black leather jacket and blue sparkly headband while she bounces to the music as she plays her violin. Justin Yu, 9, of Jericho is the cello-playing leader of the quintet whose rapport with show host Steve Harvey causes Harvey to turn the show over to Justin to emcee.

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“I got to be a host for a few seconds,” Justin says. “He gave me a question to ask Mickayla.”

The quintet’s repertoire includes pop music played in a classical style. For “Little Big Shots,” the quintet will be playing a mashup of “The Final Countdown” by Europe and Tchaikovsky’s “Swan Lake,” composed by Justin’s father, Julian, who owns the Joyous Music School, based in Hicksville.

The kids in the quintet — which include Brandon’s brother, Tyler, 9, on violin, and Justin’s sister, Christine, 6, on both piano and violin — are all students at the Joyous Music School and they started lessons at age 3. The Yus and the Laus also happen to be cousins — the Laus being Julian’s sister’s kids.

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Robin Ashbrook, the “Little Big Shots” executive producer, says the Joyous Quintet was invited to be on the show because they have “insane skill.”

This isn’t the quintet’s first big gig. A group of them played at the White House Christmas tree lighting — meeting the White House dog Bo was equally, if not more, awesome as meeting President Obama, they say. “And we toured the White House,” Tyler says.

They’ve played concerts in Hong Kong, Korea and China and on a TV talent show in Germany. They’ve appeared on “Good Morning America” and on the “Today” show. Ellen DeGeneres flew Justin to California to play on her talk show.