Ashley Emerson, Lani Corson and Stevie Dunham sit side by side, their legs swinging off the side of the stage at Penobscot Theatre. Director Mark Torres is giving rehearsal notes for actors in “A Christmas Carol,” and the girls, all fourth graders, listen with full attention. Still, their youthful energy wins out and one chews unwittingly on her shirt sleeve. Another cuddles up to an older, female actor. The third sips from a jar of apple juice.

There’s a brief break during which the girls gather at one end of the stage that has a ramp. As they talk, they prance up and down the slanted floor and giggle softly about secret comments they have exchanged.

“Places!” the stage manager calls and the girls disappear backstage. The scene begins and soon the girls ramble onstage, carrying a bench as a prop and stretching their tiny voices to project a shared line:

“And now three smaller Cratchits come tearing in.”

They pretend a Christmas goose is on the table in front of them. One even steals a thumbful of some imaginary food.

When the scene ends, the girls head for the lobby of the theater to finish their fast-food dinners. Lani gnaws on a crust of pizza. The other two sit on the floor and chat with other cast members.

Since each has been acting on local stages for at least two years, the theater has become their playground.

“It’s kind of like the stage is my second home,” says Lani, who has a major role as Christmas Past, as well as other smaller parts. “I don’t feel scared. I just feel regular.”

Both Lani and Stevie were in last year’s production of “A Christmas Carol” and agree that the show is different from others they’ve performed.

“You never have to go downstairs and wait between scenes,” says Stevie. “I like it that way because sometimes if you’re downstairs, you miss your cues.”

“You’re on all the time in this one,” adds Lani, and her smile is so full it nearly comes off her face.

“The most exciting part is meeting all the other people who like the same thing as me. They like to act,” says Ashley, who plays Scrooge’s sister, Fan, among other roles.

She breaks off into a “theater story” about when she was in the musical “Annie” and the dog playing Sandy ran offstage during an important moment. The three break into laughter.

Ashley and Lani have every intention of pursuing careers in acting, but Stevie has another plan. “I like the sea so much,” she explains. “If I can’t become a marine biologist, I’ll become an actor.”

The hard part of acting, they say, is the hours. To maintain the A’s and B’s that they all get on report cards, they have to be organized about doing homework right after school. They also have to juggle or miss other performing arts activities, such as dancing and music lessons. Dinner is usually a hamburger or pizza at the theater and then rehearsals go on until 9 p.m.

Sometimes the routine can lead to crying sessions, but each of the girls knows that’s part of life in the theater.

“It’s mostly because we get tired,” says Stevie.

“It’s mostly everything. It’s whip, whip, whip,” says Lani.

Ashley nods and adds: “Dance, voice, guitar, and theater, theater, theater.”

And they all smile their little-girl smiles and prance off to the next scene.