The hardest-working roadie at the 2013 Austin City Limits Music Festival is not the hair-and-make-up person for the Cure, nor Lionel Richie’s piano-mover, but rather, a five-foot-three, 45-year-old woman with sensibly short dirty-blonde hair, holding a pen and clipboard.

It’s 10:05 a.m. on the first Friday of the festival, and Kati Achtermann is emptying a group of singers from two buses at the corner of Robert E. Lee Road and Barton Springs Road, several blocks away from ACL’s main entrance. The buses—boxy, yellow and devoid of sleeping bunks, HDTVs, or bottles of Muscat—belong to the Austin Independent School District. The singers, 55 of them in all, are the fifth- and sixth-grade members of the Barton Hills Elementary School choir, performing in the Zilker Tent at noon.

Almost immediately, a dozen of the kids are cut off from the group as cars move through the intersection. Achtermann, Barton Hills’ principal, steps into the road to halt them, much to the surprise of the uniformed policeman who is there to do that job.

“You can’t direct traffic,” he tells her, which Achtermann finds humorous, considering the line of cars she sees at Barton Hills each day around 2:45 p.m.

“What do you think I do every day at the school?,” the principal retorts.

Along with Asleep At the Wheel (which has kicked off ACL eleven times) and local bands like Bobby Jealousy and Whiskey Shivers, the Barton Hills Choir keeps Austin City Limits Austin(ish). Backed by a four-piece band under the direction of the school’s music teacher, Gavin Tabone, they sing rock-and-roll songs, including material by the Flaming Lips, Wilco, Queen, the Beatles, and Daft Punk.

This year’s set, the Barton Hills choir’s third ACL appearance since 2009, features four songs by 2013 headliners Muse, which means Kaya Fagerstrom and Eleanor Jeansonne, the two eleven-year-old soloists on “Starlight,” get to sing the song in Zilker Park nine hours before Matt Bellamy does, albeit in G-rated fashion: Bellamy’s lyric, “Far away from the memories/Of the people who care if I live or die” has been softened by Tabone to “Of the people who care when they see me cry.”

(Jason Cohen)

Tabone, 39, has actually brought a choir to ACL seven times. From 2000 until 2009, he was at south Austin’s Palm Elementary School, where he was first inspired to move beyond the standard choral repertoire with original material, including some rock-opera style mini-musicals. Palm’s self-released CDs and ACL appearances on the “Austin Kiddie Limits” stage received a fair amount of media exposure; in 2006, they “opened” for Neil Young’s SXSW keynote and also backed up Lyle Lovett for an “Al Roker Lends a Hand” segment on The Today Show. In terms of raising the bar on pre-teen creativity, his work is of a piece with “School of Rock” (also part of ACL), Girls Rock Austin, and Staten Island, New York’s PS22 chorus.

Tabone began teaching at Barton Hills in 2009, and with Wilco and the Flaming Lips both playing ACL that year, the light bulb to do more contemporary cover songs went off. When it isn’t ACL time, the choir sticks to traditional fare: the third and fourth graders do a Halloween show, and the entire choir is a fixture with holiday classics at the Zilker Tree Lighting. In May 2012, a group of Barton Hills kids joined Pink Floyd’s Roger Waters for “Another Brick in the Wall-Part 2” at the Frank Erwin Center.

On the Tuesday before the festival, the choir has one last rehearsal. Barton Hills’ spacious music room is decorated with posters of rock icons (Hendrix, Marley, the Beatles, Janis Joplin), giant photographs of past performances, and biographical illustrations of various musical greats. There are also around a half-dozen student-drawn cartoons of “Mr. Tabone,” who is both movie-star dashing and band-camp dorky—as well as super-passionate and serious. He records and videotapes nearly everything the choir does, which is lovely for the children and their parents, but a burden for the choir director, who pores over them like Eric Taylor watching game film.

“I’m always like, ‘No, no, no, we should’ve done this, we should’ve done that,’” Tabone says. “One of my problems is I’m never satisfied. The hardest part for me with these festivals is just enjoying them. I’m always worrying about sound and the tempo and the dynamics and (stuff). I wish I could just relax every now and then.”

Really, it doesn’t get any better for a working Austin musician than Tabone has it: not only does his day job involve music, but he gets the creative outlet of the choir. He also has a “smooth funky-funk” (his words) instrumental cover band, the Gavin Tabone Quartet (GTQ), that plays a regular gig at Austin’s Whip-In, and shares some members with the choir band. (Full disclosure: I’ve known Tabone for years through mutual friends.)

This particular rehearsal is taking place in the presence of both Texas Monthly and a reporter/cameraperson from Austin’s YNN, putting extra pressure on Tabone to keep his charges focused.

“Do not ham it up,” he says, as the kids arrange themselves on different-colored risers: red and two yellows for sopranos, two greens and a blue for altos. “Our eyes are always on me, or on who?”

A unison response: “THE SOLOIST.”

“You are part of the choir,” he chides. “Be cool.”

With today’s rehearsal and three shows this week—two at the school, then ACL—Tabone knows the kids can easily get tired. “You need to think about Broadway,” he says. “They do this eight to ten times a week and still give their all every show. You need to stay in what?…”

“CHARACTER.”

“Project, smile when you’re not singing! Pleasant smile, not too big.”

You can tell the kids appreciate Tabone’s intensity. “Absolutely,” says Amy Jameson, an interior designer who’s had two daughters in the choir. “It’s not fun and games. He lets them see the professional side of it.” At Barton Hills, kindergarteners and first-graders look forward to being in the choir just like pee-wee football players can’t wait to get under the Friday night lights.

“I’ve been working with some of these kids since they were in first, second grade,” says Tabone. “When we’re in the choir, I don’t feel as much like a teacher anymore, more like the band leader.”

The rehearsal proceeds nearly uninterrupted, with Tabone highlighting a few moments where things “get a little funky monkey,” before it starts. The only major problem, on Wilco’s “I Got You,” late in the set, is one of choreography, not vocals: the two sides of the choir are supposed to alternate between wildly shaking their heads and fanning their crossed hands up to the sky, but everybody’s head keeps moving when they do the hands, ruining the visual contrast.

“It does not look good,” Tabone laments.

He ends rehearsal with last-minute instructions—when to launder the brand-new Barton Hills choir t-shirts, a reminder to drink herbal tea with honey and lemon—plus one last question.

“What’s the one thing that’s really tough for us?”

“SMILING.”

(Chan Geltemeyer, courtesy Barton Hills Choir)

The audience that gathers in the Zilker Tent at noon to watch the Barton Hills choir is mostly parents, but those parents—people in their thirties and early forties, people with tattoos, people who make art or play in bands themselves—are a big part of the ACL Fest demographic to begin with. Each child is allowed to bring one person to the show, but many families already purchase wristbands (and children under 10 get in for free). Though AISD has issued a warning to parents about letting kids skip school for ACL, being in the choir gets you off the hook, since class is almost over by the time they will be finished (they just have to sign out with Achtemann, the principal).

“A lot of artistic parents,” says Tabone. “One of the reasons I came to Barton Hills.”

Amy Jameson’s daughter Audrey, a sixth-grade soloist on the Flaming Lips’s “Race for the Prize” and Muse’s “Invincible” who also has a band (with two other Barton Hills girls and her older sister Ella), attended her first ACL as an infant–six months old. Her mother treasures the memory of last year’s festival, when Audrey freaked out watching her favorite artist, Jack White, encore with the White Stripes’ “Seven Nation Army.”

Another parent, PJ Liles, who is sporting a Van Halen t-shirt, is an iron and scrap artist and musician who appears regularly at the Maria’s Taco Express Sunday gospel brunch. “They call me the Cowboy Poet,” Liles says. “No they don’t,” his son, Levi, teases, before ticking off a list of bands he’s looking forward to. “I’m just pumped for Fun, Vampire Weekend, Muse. Passion Pit. The Walkmen a little bit.”

Showtime.

“Welcome to the Zilker Tent, ACL 2013,” Tabone says. “Once we start, we don’t stop.” The set begins with Daft Punk’s “Give Life Back To Music,” a kind of statement of intent, and a song that becomes all the more inspirational when the vocal sound is harmonizing kids instead of vocoders. Muse’s melodic bombast also feels more poignant, rather than melodramatic, in the choir’s hands. And they race right from the Flaming Lips’ “Race for the Prize” into a real barrelhouse rendition of Wilco’s “Kamera.”

Then (after another Muse song), the edgy, newer stuff gives way to classics: Creedence Clearwater Revival, the Beatles, the Beach Boys, Queen’s “Crazy Little Thing Called Love.”

“[Tabone] totally introduced us to a new era of music, like seventies and eighties,” Audrey Jameson had said earlier. “I guess it’s really good to know what, like, your grandparents are singing when they sing you a song.”

Kids say the darndest things. But, in fact, an actual grandfather, Bo Overstreet—a trim, white-haired 63-year-old whose granddaughter Evan is in the choir—says he appreciates the older songs, since he hasn’t really heard of bands like “Wilcot.”

Wilco’s “I Got You” bring the last part of the set to one crescendo, with the head-and-hand thing now completely fixed. The final crescendo comes on the last song, Muse’s triumphant anthem “Knights of Cydonia” (a song the band itself will encore with later that night), which is literally fist-pumping: that’s the choir’s choreographed move, and every parent’s pumping with them. Nobody has to be told to smile.

And nobody’s smiling wider than Tabone—though later, watching the video, as he sheepishly admitted in an email to the parents, he discovered he was unwittingly yelling at the kids: “You’re kicking ass!”