Oakton High School students are getting an opportunity to see one of their favorite teachers unravel in front of a crowd, but it’s not what one might think.

Drama teacher Vanessa Gelinas stars in “God of Carnage,” a dark comedy by French playwright Yasmina Reza about two sets of parents thrown together after a playground fight between their 11-year-old sons.

In the play, the adults meet to hash out what happened on the playground between their children. But the result of this well-mannered attempt at civility is some adolescent behavior in a living room setting.

The play is being staged at Signature Theatre in Arlington County.

Gelinas, of Reston, portrays Annette Raleigh, the mother of the aggressor in the story.

“She’s in wealth management, and she’s married to a lawyer,” Gelinas said. “She’s a full-time working woman, and her husband travels about. . . . You get the sense that she’s not as hands-on as the other parents [of the victim in this story]. There’s some guilt there for her in that.”

Dressed in a power suit and smugness, Gelinas’s character goes from hair-up, put-together professional to hair-down, pillow-wielding pariah during the one-act, 70-minute production.

“I am also a working mom, so I kind of understand where she’s coming from,” said Gelinas, whose son is 10.

While performing in the play allows Gelinas to take lessons from the classroom to the stage, the opportunity has meant balancing her day job with being a professional actress.

During the play’s rehearsals, which began in March, Gelinas took three weeks of leave from teaching.

“I had to give up vacation time to make this work,” she said. “Now I’m teaching during the day and performing during the night. When I get home, I need to come down. I organize my closet and stuff like that.”

Practicing what she preaches in her classroom means long days. Gelinas performs eight shows per week, with no shows Monday nights and two on Saturdays and Sundays.

“It’s what I went to school for,” she said. “I didn’t set out to be a teacher. . . . What it’s taught me is that I really like to be a director.”

Like a baseball coach stepping up to bat, Gelinas said, “it allows me to use that muscle that I haven’t been able to use.”

Oakton High School senior Joe Flynn, 17, saw Gelinas perform recently and said it gave him a new view of his teacher.

“I loved it. Seeing a teacher perform on stage gives you a new respect for her,” said Flynn, who wants to be an actor. “When people think about high school teachers, they think — not that they’re dried up — but that they aren’t doing much anymore” in terms of outside of the classroom. “Aside from the stress level of being in a show and teaching, you can see the difference between when she’s in a show and not in her level of happiness. She’s just happier.”

Junior drama student Caroline Werenskjold, 17, agreed. “She always comes in and brings new ideas to our rehearsals. . . . She has more creative ideas about how to deal with things,” Werenskjold said.

Although she and Gelinas bicker on stage, Naomi Jacobson, the other mother in “God of Carnage,” said having a teacher also perform professionally is of great value to Oakton’s students.

“I think Vanessa’s students are incredibly lucky to have a professional actress of her caliber who has chosen to teach at the high school level,” said Jacobson, an adjunct professor at the University of Maryland. “Her craft, artistry and understanding of the practical demands of performing, not just theory, make her a valuable resource, especially for any of those students who are considering theater or film as a profession. They will be way ahead of the game when they go to their next level of training.”