In a darkened gym at Valley Day School in Morrisville, five teenage girls slowly stretched and arched their way into a previously unfamiliar world of modern dance, as two drummers tapped out a back beat.

The new dancers moved tentatively and then more enthusiastically – crab walking and then skipping and leaping across the stage. But their visiting instructor, Erin Carlisle Norton of a troupe called Moving Architects, wasn't interested in how the girls moved as much as how they felt.

"I feel more confident without boys," one of the dancers said, as the others smiled even as they worked up a sweat. "We can talk about our girl issues."

If it sounds therapeutic, that was the point. The dancers from Valley Day School – a K-12 Bucks County school for kids requiring emotional and academic support – worked with the Moving Architects crew for three days and called themselves the Leading Ladies Girl Group. The program aims to use dance movements as a way for female teens to give voice to emotions they find hard to express in words.

"At first, they were hesitant — to see them come out of their shell and slowly open up was something," said Norton, whose small dance outfit is based in Montclair, N.J.

Valley Day officials said they created the Leading Ladies program – with roughly 12 participants from the school's enrollment of about 90 – both to recognize that the predominantly male school has been increasing its female enrollment and to find new ways for these girls to address their emotional issues and any past trauma they experienced.

"This is out of their comfort zone," said Stacy Maurer, the school's licensed clinical therapist, who organized the Leading Ladies and watched approvingly from the wings as Norton guided their moves. To the dancers, she said, "What I have to say is, once you got into it, you couldn't wipe the smiles off of your faces."

The Leading Ladies were also taking on a starring role in a hot topic of youth psychology – how to account for differences between boys, who are often more verbal and forceful in expressing or acting out emotions, and girls, who are more prone to hold back and repress their feelings, which in the worst cases can result in depression or behavior such as eating disorders.

Valley Day officials, in a release announcing the program, cited the #MeToo movement against sexual harassment and assault as evidence that girls experience different types of trauma. They also said that therapeutic approaches are needed that recognize young female brains are wired differently than those of boys.

It's a concept that clearly resonated with the visiting Norton, who has said that a key mission of Moving Architects – developed in part by focusing on trauma in training exercises with New York's Gibney Dance – is to foster the idea of merging femininity with strength.

She said the idea for students is to "try something new and step out of their comfort zone and feel themselves succeed in that." She said some of the exercises involved girls writing their feelings on a sheet of paper and then working on dance moves – a fast and loud stomp for "anger," for example – to act it out and thus feel empowered.

(Norton and Moving Architects also teach dance to boys, both during the three-day residency at Valley Day, where they worked with all students, and elsewhere.)

Inside the gym, Norton told the girls in the Leading Ladies group that "our bodies are super important to us" as a way to express feelings. "I know this is new and may feel kind of strange," she added, "but let's just go for it."

"I liked how you could tell that in dance they're trying to let something out, they're trying to express something with dance instead of words," said 15-year-old Jaida Santiago, a 10th grader who said she has experience in dancing ballet and salsa, but nothing like this before. "I was having a little rough day until now. I was really tired, but this energized me."

In addition to working on their own routines, with an assist from one of her New York dancers, Caitlin Bailey, Norton showed the girls a video of Moving Architects giving an intense and emotional performance, titled "Enough," about gun violence. One student said the dance looked like fighting, while another invoked robots.

"You guys aren't too far off," Norton responded. "It shows strength. You could express all these things with your body."

One of the Valley Day dancers, senior Trinity Brown, had to be coaxed into participating but was enthusiastic by the end of the session. "It helps me express myself and get through some stuff, get through emotions," she said, adding that she's weighing a future as a dancer if she doesn't become a writer or a therapist.

Several of the girls told Norton that they felt more comfortable with no boys around and less self-conscious about the sweat of intense dancing.

"Why do they not seem to care – and we do?" Norton asked.

The answer shot back quickly: "They're boys!"