By SOPHIE DWECK

On the outside, Brooklyn’s James Madison High School looked empty and quiet—after all it was a Saturday night. Who would be going to a school at that time?

But on the inside, it was quite the opposite. The energy was high and the place was bustling. You could feel it, the excitement in the air. The chattering echoed around and against the marble lobby floor. There were warm embraces and all sorts of flowers and gifts. Students, glammed up and adorned in different colored costumes, rushed around to get where they needed to be.

In the distant background, the diffused sounds of an orchestra played. The drums thumped and set the beat, and the string instruments whined, all while the woodwinds released their jazzy, sultry timbres around the building.

It was the start of another SING!—a popular performance competition that has thrilled high school students for some seven decades. But this time spectators saw New York City Schools Chancellor Carmen Fariña at center stage in the Sonia Lerner Auditorium.

That’s because SING! is catching on: She was there to promote the expansion of the student musical program to an additional 10 high schools, making it 20 all together throughout the city.

“There’s joy in the building, which what all schools should have,” the schools chancellor said, while the words “BROOKLYN SINGS!” were projected above her head. She said the judges were principals who would have the competition in their schools the following year.

Created in 1947, SING! was conceived by music teacher Bella Tillis of Midwood High School, Madison’s rival. The traditional musical competition between various grades allows students to showcase their creativity by writing a script with original lyrics put to popular tunes—and then to perform it and do behind-the-scenes work like lighting, set and costume design. Singer-songwriter Carole King, a Madison alumna, noted in her autobiography “A Natural Woman: A Memoir” that she volunteered musically in the annual SING!

Starting in 2014, the three main high schools in the Midwood area of Brooklyn—James Madison High School, Midwood High School, and Edward R. Murrow High School—expanded the concept through an inter-school performance competition called InterSING!

The expansion began thanks to country and pop music megastar Taylor Swift. While promoting her fifth album, “1989,” she announced on ABC’s The View that she’d be donating all the proceeds from her hit track “Welcome to New York” to the arts program in New York City public schools.

“The fans were wonderful enough to make it number one on iTunes,” Swift said. “It’s selling really, really well, which is good because I’m donating all of my proceeds to New York City public schools.”

Subsequently, Fariña chose to allocate Swift’s $50,000 in donations toward the expansion of the SING! program. All together, $122,000 in contributions has been donated to the program for the 2015-2016 school year, according to a city Department of Education press release.

“It’s so much more than what [the students] are doing for the production and what they’re doing when they’re in high school,” said Murrow’s SING! coordinator, Bonnie Shapiro. “They learn so much from it that they take it with them in other aspects of their life.”

The students learn leadership skills by working with their peers. Sometimes, friendships need to be set aside for the good of the show, helping students to understand professional relationships and responsibility.

“It’s important because sometimes this is where they realize what skills they have, what talents they have, what their interests are,” Shapiro said. “Whereas they didn’t know that before just from their academic classes alone. This gives them an opportunity to open up to other experiences.”

Shapiro, who has been teaching Italian and Spanish for almost 17 years, participated in SING! when she was a student at Midwood, which led to her role as a coordinator. “I oversee the production,” she said. “It’s more administrative. It’s not on the creative end.”

Just as the show was about to start, Fariña exited the stage, remarking, “Hopefully no one will break a leg, but break a leg.”

The lights suddenly went out and then abruptly shined on the student orchestra—the Freshman-Seniors, (also known as Senior-Fresh), of Murrow were up first.

Immediately the 60-student orchestra started its own version of Sugar Hill Gang’s “Rapper’s Delight.” Everybody already knew it was going to be a good night ahead.

The plot was a modern-day twist on classic ’80s flicks “Fame” and “Footloose.” The students of Senior-Fresh Prep High School, a school dedicated to the arts, were revolting against their new, evil principal who was trying to get rid of the program. The students find out that the principal actually works for another arts school and expose him.

Next up was Madison’s Freshmen-Juniors team. They spun a tale of two materialistic teenage girls who join their grandparents at alumni night at Madison High School, but end up taking a faulty elevator and going back in time. After getting lost in many decades, the girls realize there is more to life than social media and technology.

Midwood’s Seniors told the story about a young tourist from Hawaii lost in New York City, trying to find her way to Times Square. She comes across a director, under cover as a homeless man, who takes her around the city on the subway and in taxis—normal touristy things—and subsequently makes her into a Broadway star.

Cheers mingled to the point that by the end of each show, it was hard to decipher who was there for whom, but either way the cheers for each school were equally as loud. The night was filled with dancing, acting, and singing.

Finally, the results were in. The stage was packed with each of the casts cheering and singing to the Beastie Boys anthem “No Sleep Till Brooklyn.”

“The winner of the 2016 three-in-SING is…Midwood High School,” one of the judges yelled.

The stage and audience erupted in cheers and rounds of applause. For the first time, Midwood had beaten the unbeatable Murrow.

And it was all for a good cause.

In 2014, Joe Gillette, who runs Relay For Life in nearby Bergen Beach, Mill Basin, and Marine Park, approached the Madison, Midwood, and Murrow principals and SING! coordinators to see if they’d be interested in a three-school competition to raise money for cancer research.

“Being that the three schools are some of the best large high schools in New York City and we do a lot of charitable work for different organization, we jumped right on it,” Shapiro said.

Over the past three years, InterSING! has raised about $50,000 for Relay For Life, according to Shapiro.

She said that ultimately the students don’t care who wins because they’re raising money for a good cause. “It becomes more than just the competition and they realize the true value of something like that,” she said.