This post is part of Mashable's ongoing series The Women Fixing STEM,(opens in a new tab) which highlights trailblazing women in science, tech, engineering, and math, as well as initiatives and organizations working to close the industries' gender gaps.

With patience, Emily Cruz detangled a vine with Dorito-shaped leaves from a fallen branch, unwinding it slowly and then pulling it out from the roots.

The 12-year-old and 40 other middle-school girls were working to remove what’s known as mile-a-minute vines(opens in a new tab) recently from New York City’s largest green space as part of a program aimed at encouraging girls to pursue environmental science. Over the years, the fast-growing plant has elbowed its way into Pelham Bay Park in the Bronx, which is more than three times the size of Manhattan’s Central Park.

“Invasive means they’re not from here,” Emily explained, still concentrated on the thorny plant as bugs buzzed around her. “We’re getting rid of them because they wrap around young trees and make it hard for them to grow and reach the light.”

Emily and the other girls were observing the plants with Green Girls(opens in a new tab), which is run by the City Parks Foundation(opens in a new tab). It’s expanded from a three-week summer program to a five-week course that runs year-round since it started in 2002. While the summer program investigates urban forests, the focus is on drinking water during the school year. The key to its success, program leaders say, is the confidence the in-the-field activities give the girls. At a time when environmental professionals complain of a "leaky pipeline," Green Girls aims to plug the holes.

In the U.S., women hold only 24 percent of STEM jobs despite making up 47 percent of the workforce, according to a 2017 report issued by the U.S. Department of Commerce(opens in a new tab). Green Girls Director of Education Chrissy Word thinks the gap has its roots in early education. 

“Female students and students of color have gotten messages in different ways that, when it comes to science, they should step back and shouldn’t put themselves out there,” she told Mashable.

Word’s sentiment is backed by research(opens in a new tab). A New York University study(opens in a new tab) from last year found six-year-old girls less likely than boys to see their gender as “really, really smart,” suggesting these gender stereotypes start early. Green Girls administrators were aware of these issues when planning the curriculum. By creating safe spaces, providing female role models, and emphasizing growth, they see their program as uniquely poised to boost girls’ confidence.

The girls think so, too.

“I think it matters that it’s all girls,” Leah Tamayev, 15, said while throwing a huge bundle of vines into a pile. “A lot of us are more shy at school, including me. But now we’re really comfortable with each other.”

Sian Beilock, a cognitive scientist who’s studied women in STEM and president of Barnard College, told Mashable that the classroom environment can have a big impact on how girls see themselves when it comes to career choices.

“In the classroom, to say nothing about pop culture, kids get messages on many levels about activities and behaviors that are for boys or girls,” Beilock said. “This is harmful because when girls think they aren’t good at math and are anxious about it, their math learning can suffer [and] these negative effects can have a lasting impact.”

In some ways, Green Girls resembles Girl Scouts, minus the badges and cookie selling. Half of the time the girls are searching for bugs and arguing about what kind of grasshopper species they found — it’s not a conehead, it’s a fork-tailed bush katydid!

When one girl left the program early for the day, the others named a team (they were playing a game during a break) after her favorite plant, sassafras, which she likes because its roots smell like fruit loops. “I miss Alyssa!” the girls chanted.

In addition to making it feel like camp, the outdoor classroom allows girls to interact with the nature they’re learning about. “You may think it’s boring to learn about the environment, but you’re probably not learning about the details,” Mritika Rahman, 12, said. “We learn in school that there are things called invasive species, but here we’re seeing them.”

This is what Word means when she talks about in-the-field learning. “They’re seeing the impacts and they’re starting to think, what are some solutions, and how do they play a role in this?” 

Confidence boosting is ingrained in Green Girls, but not everything is focused on success. Leaders also teach girls how to manage failure, which research shows(opens in a new tab) can matter especially in higher education when the work gets harder.

For girls self-conscious about their intelligence, a failure on a test can feel like proof that they aren’t smart enough, but at Green Girls, failure is seen as an opportunity to learn. When a girl makes a mistake, it’s often another participant who helps her address it.

When Emily, the girl detangling the vine with Dorito-shaped leaves, saw her friend Leah repeatedly prick herself with the vine’s thorns, she suggested she pull the plant from the roots. 

“Like this?” Leah asked, adjusting her technique.

Still, with so few women of color in STEM, it can be hard for these girls, many of whom are Latina and black, to imagine themselves as leaders in the industries. 

“A lot of girls want to be actresses or models,” related N’Kaylah Simmons, 17, pausing to develop her thought, “and sometimes I think, do they actually want to be these things? Or is it because it’s the only thing they see?”

For women of color, navigating STEM means dealing with racist stereotypes in addition to sexist ones. A Pew Research report(opens in a new tab) from earlier this year suggests women of color are more likely than white women and white men to doubt their abilities. And because the majority of students in Green Girls are women of color, administrators make a point to hire female professionals who look like them to talk about how they navigate multiple stereotypes.

Giving young women of color access to these kinds of mentors is important not only to combat stereotypes, but to prepare them for hostile work environments. According to a 2017 study(opens in a new tab) published in the Journal of Geophysical Research that surveyed 474 astronomers and planetary scientists, “women of color experienced the highest rates of negative workplace experiences, including harassment and assault.” Forty percent of respondents who were women of color felt unsafe at work due to their gender or race.

By explicitly seeking out women of color as lecturers and encouraging Green Girls entering high school to sign up as interns, Word hopes to create a network of women that can help each other in each stage of their STEM career.

Before leaving, Green Girls intern and former participant Erica Morales Armstrong had forgotten her skateboard. “Wait up!” the 16-year-old screamed, running back in the direction of the forest to fetch her board. After retrieving it, Erica reflected on the day’s lesson.

“I always forget how tiring removing invasive species is, very hands on,” she said, still catching her breath. Then she smiled, “but that’s what makes it fun.”