For anyone feeling wistful about the disco craze and ’80s synthesizers, take heart: Today’s teens understand that the albums of the Bee Gees and Wang Chung are crowd-pleasing dance hits.

A singer and dancer in her high school show choir, Emily Karr especially takes delight in performing “Night Fever.” Karr and other members of Cadence, the coed choir at Carmel Catholic High School in Mundelein, pay homage to the 1977 “Saturday Night Fever” soundtrack — not as an excuse to dress up in bell-bottom pants and platform shoes, but as a groovy celebration.

“I felt it in my heart,” Karr said after taking the stage Saturday at the Chicagoland Showcase.

With its whirlwind, quarter-hour routine, Cadence joined high school show choirs from across the suburbs and the Midwest at the elite competition hosted at Hersey High School in Arlington Heights. Now in its 26th year, the event is an exercise in versatility.

In each routine, choirs sing across genres and eras. There are mid-performance costume changes and tonal shifts. And the facial expressions? Anything but subtle.

“It’s the glitter, the hair, the family, the friends, the long hours together,” Karr said of her love for the world of show choirs. “It’s just so exciting and glamorous and fun. It doesn’t matter at the end of the day if we did bad or if we did good — just know that we did it together. We’re a team.”

Cadence Director Joyce Haqq couldn’t see much of that from her spot conducting the live band behind the stage, but she certainly heard her students feeding off the audience.

“I’m thrilled. I told them before we started that I was already proud of their awesomeness,” she said.

In her first year directing the group, Haqq arranged a retro set transitioning from DeBarge’s “Rhythm of the Night” to “The Music of the Night” from Andrew Lloyd Webber’s “Phantom of the Opera” to “Night Fever” and Wang Chung’s “Everybody Have Fun Tonight.” Sense a theme here?

“I’m a child of the ’80s, and so it seemed like a really fun idea to do ’80s music,” she said.

Judges are so meticulous they use tape recorders to document their reviews of choreography and vocals.

“They even judge how we prepare before we go on,” Haqq said.

“The second we step on the stage, that’s part of being judged, which felt like more pressure at the time than the actual performance.”

The actual performance was bittersweet for Karr, a senior who soon will be leaving for Marquette University.

“I really wish I could do it again,” she said. “I’m excited for my group next year. They have some really exciting plans, and I wish I could be a part of them, but I will come back and watch every year.”