Singing teen Jackie Evancho doing what she loves at The Smith Center

Jackie Evancho turned 13 on Tuesday, and needless to say, the “tweener” divide between child and adult is more pronounced than usual. On the adult side of the divide stands the small person with the giant voice, singing in front of an orchestra Saturday at The Smith Center for the Performing Arts.

And on April 26 (here in Las Vegas), Jackie will be on the big screen as Robert Redford’s daughter in “The Company You Keep”. The political thriller is an independent release, so in some cities it opened April 5, closer to her birthday.

So when Jackie was here last month, rehearsing for her part in Cirque du Soleil’s “One Night for One Drop” benefit, the notion of a big-screen debut appealed to the younger side of her: “That’ll be fun. I can go to see it in a theater with my friends on my birthday.”

Jackie was excited by other elements of the appearance for the One Drop foundation, none of them directly related to that soprano voice of a prodigy which no one can really explain. Sure, she sang “Bridge Over Troubled Water” in full operatic tilt at the benefit, even as she battled a flu that had made her violently ill the night before. But the bigger appeal? Being lowered 100 feet to the stage of the “O” theater for the show’s grand finale, centered in a giant circle wearing an angelic train. “I was superexcited,” she says of first hearing about the plan.

Just as exciting, on this afternoon at least, was the swim test required for anyone who performs on the “O” stage (even when it’s covered with decking, as it was for her song).

Jackie’s mom calls her “little fish,” she says, and she’s been too long away from the water this winter. “I always put myself up to a challenge,” she says. Once, back in her pre-“America’s Got Talent” grade school days in Pennsylvania, she made the “Kangaroo Club” for jumping rope a full minute without messing up; the class was told it was a practice run but it turned out to be the real test for those who hung in there.

A bigger challenge still came with “Talent” in 2010. Her family already had steered her through the recording of an independent album, “Prelude to a Dream”, released when she was 9 to negligible results. But then she became the audience favorite on the NBC talent show.

Las Vegas bluesman Michael Grimm eventually pulled the upset to be the season winner. But by the time the finale aired, Jackie already had caught the attention of record producer David Foster and, it turns out, Redford .“I’m sitting in the hotel room and I’m surfing TV, boom there comes this beautiful, angelic face on a show called ‘America’s Got Talent’, ” Redford told Extra. “I thought, maybe she could act. It was a risk. ... It goes to show you risks are worth taking; she turned out to be the most real, human kid.”

That may be born out by the fact that, after three years of touring behind two Foster-produced albums and a PBS special, Jackie says her grand descent in the “One Drop” benefit was “finally my moment where I could feel like a big superstar.” She says she understands her extraordinary life. “It’s just, I never really feel like I’m a star. I’m just doing what I love. And a lot of people say that to be famous you can’t do things that you love all the time. But I think that what I’m doing now is exactly what I was looking for. I never really imagined I’d be a star. As a matter of fact, I still don’t feel like I’m a star.”

The big question, of course, is what will happen when she gets older, when the voice is less a novelty for coming from an adult. David Foster said in 2011 that her musical instincts are genuine, and she could be “the greatest opera singer of her time ... if that’s what she wants.” “If anything I think that my voice will be a lot more grand when I get older,” Jackie says. “As you get older through the years your voice will just eventually mature and keep maturing. I don’t think there will be a time it will stop until you stop growing.” But that will all come in time. For now? “I’m getting a dirt bike for my birthday! yippee!” she Tweeted last week