It started in high school, when Marie Wolbach was the only girl in her physics class. And then, later in life, after she had children, she decided to go back to school and was denied even an application to the University of Utah's physician's assistant program.

A generation later, when Wolbach's daughter arrived at her own Advanced Placement physics class in high school in Palo Alto, she was told she shouldn't raise her hand in class.

"That was the pervasive attitude, even a generation after me," Wolbach said. "That all together just made me think – waiting for something to happen that changes it is going to take some catalyst, but I wasn't in a position to do anything about it then."

But then, in 1991, she was spurred to action by an American Association of University Women (AAUW) study, "Shortchanging Girls, Shortchanging America," that showed young women tended to drop out of science and math courses during middle school. She ran for a position on the AAUW state board (and got it); floated her idea to run a math-and-science camp for middle school girls; and by 1998, opened the first Tech Trek Science and Math Camp for Girls at Stanford University.

Wolbach, a Palo Alto resident, received a prestigious national honor in June for her leadership of the Tech Trek program, which has now grown to more than 20 camps based at universities and colleges throughout the United States that have reached more than 9,000 young women. She was one of five national winners of the Jacqueline Kennedy Onassis Medal for Public Service, part of the Jefferson Awards Foundation, "the country's longest standing and most prestigious organization dedicated to activating and celebrating public service," the foundation's website reads.

Tech Trek is a volunteer-driven program; everyone from junior counselors to dorm mothers to directors are volunteers, many of whom once attended the camp themselves, Wolbach said. (The organization pays the teachers who lead the camp classes.)

During the weeklong summer camp, girls choose a specific "core" subject to focus on – forensics, marine science, geology, engineering, coding or the like – and spend three hours each morning learning about that subject. The afternoons are for outside-of-the-classroom activities, which could be anything from throwing a Frisbee (which accomplishes a dual purpose of getting exercise and learning about physics) to field trips (past excursions have included the Computer Science History Museum in Mountain View, the Stanford Blood Center and the Exploratorium in San Francisco).

In the evening, the girls participate in large-group activities from astronomy lessons to talks about how to prepare academically and financially for college. The camps also have a "professional women's evening," in which 10 to 15 women in science-related professions volunteer their time to talk to the girls and answer questions in small groups, Wolbach said.

The girls themselves, mostly rising eighth-graders, are selected by their school teachers to attend. The camp is also set apart in its cost: Families are only asked to pay a $50 fee, and the rest is covered by sponsors and donations. Wolbach said many girls who attend come from low-income backgrounds and go on to be the first in their families to graduate from high school or go to college. She remembered one girl in particular from Sacramento who had never seen the ocean until she drove to the Stanford camp.

"She looked around and said, 'I'm not sure why I'm here because these other girls have a lot more experiences and more money,'" Wolbach recalled. "I said, 'That's not the point of the camp. That has nothing to do with the camp.'"

Two months after her week at Stanford ended, Wolbach heard from the AAUW branch president in Sacramento that the girl – incredibly quiet her first few days at Tech Trek – had run for class president and won. She said giving middle school-aged girls that boost of confidence and self-assurance is the "unspoken goal" of the STEM (science, technology, engineering, mathematics) camp.

In a 2013 survey of Tech Trek alumnae who attended the camp in California between 2006 and 2009, 91 percent of girls reported that Tech Trek boosted their self-confidence in their ability to be successful in science classes, and 78 percent said the same for math classes.

Eighty-two percent of respondents said they chose to take more science classes in high school because of Tech Trek. By 2009, 87 percent of respondents had completed algebra II, compared with 78 percent of female students and 73 percent of male students nationally.

Wolbach acknowledges there's still a ways to go before future generations of young women don't have the experience of being the only girl in the room.

"It's getting that critical number so they're not the only girl in the class. Five years in, I was still talking to graduate students at Stanford who said, 'It's still really hard; I'm the only girl in the department or I'm one of two.' So now we're trying to get to that critical mass where it's just accepted as well as any other profession," she said.

But Wolbach is cautiously optimistic. She said when she first started Tech Trek and would use the term STEM, "almost nobody knew what it stood for."

"Nobody had the idea that girls would really like to go to science camp," she added. "It was really not on the landscape yet then and now it's everywhere."

(Simply Google "girls' STEM camps Bay Area" and there are endless hits -- university-based camps, "adventure camps," science internship programs, community organizations, online classes and more.)

Wolbach hopes, at some point in the future, Tech Trek will no longer exist because it won't be needed.

"I don't think it's happening in the next very few years, but the amazing turnaround in 18 years gives me confidence," she said.

Wolbach, who received her Jefferson Awards gold medal at a ceremony in Washington, D.C. in June, noted that she's in good company. Palo Alto couple Vic and Mary Ojakian won in 2013 for their extensive suicide-prevention and mental health efforts and Palo Alto mother Olenka Villareal in 2014 for her creation of the Magical Bridge playground in Palo Alto, one of the only in the country geared to the needs of adults and children with disabilities.