“Guess who I played?” the Cary second-grader demands. “Guess.”

The Big Bad Wolf? She nods, excited. “I had a visor and a T-shirt with a wolf head on it,” she said. At 7, Mary Kate’s view of the world is much like any other girl in elementary school. She likes to dress up and play with her friends.

She just does it with a bigger audience.

Since she started acting four years ago, she’s been in five commercials, has a recurring role on “One Tree Hill,” and is now the youngest cast member in North Carolina Theatre’s “The Sound of Music.”

“I started dancing when my legs were long enough to dance,” she said. “I started singing when my voice was trained to talk.”

Her mom, Jennifer, and dad, Robert, were reluctant to turn what they thought was a fun hobby into anything serious. But Mary Kate and Ray Walker, a Broadway actor who taught her at NCT, wore them down.

“Mr. Ray said that my husband and I should listen to the strong desire she has to sing and dance,” said Jennifer, a stay-at-home mom in Cary. “She’s been telling us that since she was 2-and-a-half, pointing at ‘Barney,’ saying ‘I want to do that.’”

And Mary Kate has never looked back.

A tough decision

Jennifer remembers sitting nervously in the audience for Mary Kate’s first big tap routine on stage. There were about 600 people in the audience. Mary Kate was 3.

“I remember thinking, ‘there’s no way she’s going to remember this routine,’” Jennifer said. But Mary Kate remembered. “Then I said, ‘OK.’ For her, even then, it was this very serious, intense thing.”

Mary Kate took two semesters of classes at NCT before her teachers urged her parents to take notice that their daughter was gifted.

“My husband and I said, ‘we’re not interested.’ She’s a cute kid, but really?” Jennifer said. “We are her biggest fans but we were worried. Neither one of us knew about theater professionally, and we thought she’d be exposed to things we didn’t want.”

“But I said I wanted to do it,” Mary Kate said.

They eventually signed her with Kids Unlimited Talent, an agency in Raleigh. Soon she was auditioning for an Adam Sandler movie where she had to do something both she and her mom didn’t like.

“She had to throw a tantrum,” Jennifer said. Mary Kate made a face. “She’s not right for that.”

After the audition, Mary Kate’s agent called back with another opportunity: a guest spot on “One Tree Hill,” a popular TV show about two half-brothers living in a small town. It films in Wilmington, a two-hour drive from Cary. Mary Kate nailed the role of Lily Roe Scott, little sister to Chad Michael Murray’s lead character.

“When you are Lily, you’re just a fun person,” Mary Kate said. “She’s just a teensy bit shy.

“I’m not shy,” she added.

Sound of hard work

“She’s delightful. She’s very quick,” said Richard Stafford, the director for “The Sound of Music.” It’s his first time working with Mary Kate, but not his first working with a young actor. It’s a demanding rehearsal schedule — several days a week, upwards of seven hours at a time — but Stafford said Mary Kate holds her own.

“She listens and has a wonderful sense of timing, particularly for someone so young,” he said. “She has quite a big responsibility in the show, dancing and singing with the more experienced kids.”

For Mary Kate, being part of a major stage production also means missing some of her friends’ get-togethers. Jennifer said that, given the option, she’s pragmatic about it: An audition or play is a one-time opportunity, and she can always reschedule a play date.

“I forgot Lana’s birthday was this week, so I said, ‘Lana, I can’t go to your birthday party, but you can come to ‘The Sound of Music,’” Mary Kate said.

Jennifer said that most of the their friends and neighbors don’t know about Mary Kate’s high-profile modeling and acting gigs.

“I’d say the majority of people at her school are unaware of her jobs,” Jennifer said. “I’d get an e-mail and they’d say, ‘I saw someone who looks just like Mary Kate.’”

But more of Mary Kate’s friends will get to see her acting side soon. Many of her classmates and teachers are planning to see her perform live in “The Sound of Music,” which runs July 25 through Aug. 2 at the Raleigh Memorial Auditorium.

As far as nerves go, Mary Kate has a system.

“I have a little notebook inside my brain,” she said. “I’m pretty little, so I don’t have many lines.”

So far, the Englehardt family is taking it one show, one commercial and one play at a time with their only child. Dad Robert has a local oral surgery practice and Jennifer loves living in Cary. Plus, Mary Kate loves going to school and Jennifer doesn’t fancy the idea of any on-set tutors.

But will Hollywood ever replace Cary as home?

“We don’t have any plans,” said Jennifer. “Although two years ago, if you asked me if I’d let her be on stage, I would have said no. A TV show with so many viewers? I would have said no.”

For now, Mary Kate says no too as far as moving anywhere else for her career. She has another commitment keeping her at home: a band she’s formed at school. They practice at recess.

“I’m the lead singer,” she said. “Our name’s ‘The Girls of Heart.’ But we’re still working on it.”

For tickets to “The Sound of Music,” call Ticketmaster at (800)745-3000 or contact the N.C. Theatre Box office at One East South St., Raleigh or 831-6941, ext. 6944. For information about acting and singing classes, or upcoming shows, visit nctheatre.com.