At the second of two meetings Sheryl Sandberg had in Minneapolis on Tuesday night with readers and fans of her recent book, a few members of a critical audience were present: teenage girls.

One of them was Sarah Borntrager, 16, who listened closely as Sandberg, the chief operating officer of Facebook Inc., encouraged a group of female military officers and federal staffers to “lean in,” the admonition that became the title of her bestseller, which sparked a renewed national conversation on women and workplace issues.

Borntrager, a junior at Farmington High School and daughter of a woman who is a civilian Air Force financial analyst, said girls too often lean back.

“I see that actually a lot in high school,” she said. “Someone who tries to make a stand for something, a girl, will be seen as obnoxious, as if she just keeps rambling, but a guy will be able to get his point across and be listened to. It’s something that shouldn’t be.”

Sandberg gave a keynote speech at the Grace Hopper Celebration of Women in Computing on Wednesday, the nation’s largest annual conference of women in high-tech. The night before, she visited two of the thousands of Lean In circles that have sprung up since her book was released in March. Nearly 300,000 people have registered their support on Facebook for the Lean In Foundation, which receives all proceeds from sales of the book. About 9,000 circles have registered, and many more are active but unregistered.

Linda Brandt, a public health specialist for Hennepin County, describes her circle as “Girl Scouts for adults,” and she hosts a group of about 30 at her home in southeast Minneapolis.

The women — ranging from photographers to dancers to librarians to advertising professionals — packed into Brandt’s living room waiting for Sandberg to arrive. Among them was Sandberg’s mother-in-law, Paula Goldberg, a prominent Minneapolis resident and executive director of PACER, an antibullying group that advocates for children and young adults with disabilities.

When the black Chevy Tahoe pulled up to the front of Brandt’s home, the doors popped open and Sandberg beamed as she started meeting the women. “Oh my god, this is so exciting!” she said.

The women introduced themselves one by one and explained what they think the Twin Cities contributes to the Lean In movement.

“I think Minneapolis has an incredible community of both really powerful businesswomen but also a thriving arts and communications and advertising and, you name it, people do it here,” said Michelle Chester, an advertising brand strategist who lives in Minnetonka. “So I think that combination of left- and right-brain leaders is really valuable in the Twin Cities area and I also think there’s something to be said for being a powerful woman sitting at the table but also still maintaining your Minnesota Nice, because that’s part of who you are when you’re born and raised here.”

Other women mentioned the scrappiness of Midwesterners as an important contribution to leaning in, the inventiveness of the Twin Cities and its diverse economy.

Sandberg makes an economic case for the Lean In movement, and she likes to bring up Japan, a country with one of the lowest rates of workforce participation by women. Japanese women often stop working when they have a child, and Goldman Sachs projects the Japanese economy could be 15 percent bigger if 8 million more women worked.

“Japan’s GDP cannot grow unless they get more women in the workforce,” Sandberg said. “In two decades, three decades, the U.S. could face the same problem.”

In order to continue to grow, the United States will need the full participation of the workforce, she said, which will require women to step up and their partners to split the work at home, something that she said is still not happening enough. When it comes to particular firms, any company with strong female leadership has a competitive advantage over those who do not, she said.

“This is about our economic growth,” Sandberg said.

One criticism the superstar Facebook executive has taken since publication of the book is that she’s an elite. She went to Harvard, was mentored by former Treasury Secretary Larry Summers, and after perfectly timing her transition from Washington to Silicon Valley, became extremely wealthy.

Anna Picchetti, a product manager, said the group at Brandt’s home helps refute that criticism. The group is racially, demographically and professionally diverse, and the women live in a place that has been rated by Intuit as the fifth-best city in the U.S. for women entrepreneurs. The fact that the group is not elite, yet draws powerful inspiration from Sandberg, lends a certain grass-roots credibility to the Lean In movement, she said.

“It’s not just a corporate movement, it’s a movement for anyone who wants to lean in to their life, their job, their whatever, and I think this group, thanks to Linda, is a really good representation of that,” Picchetti said.

The circles can serve whatever purpose the women want, Sandberg says. They’re modeled on microcredit circles and book clubs. “Book clubs with a purpose,” she said.

Even in the same occupations, women only earn 93 cents for every dollar men earn, and across the population, women earn 77 cents for every dollar men earn, partly because women tend to choose lower-paying professions. A big part of what explains both discrepancies and the lack of female leadership in the world’s biggest companies is that women too often fail to display self-confidence. The result, Sandberg said: “Women are just as much a part of gender bias.”

At the Hopper conference, Sandberg told her audience to ask themselves what they would do if they weren’t afraid, then do it. She admitted that even she occasionally struggles against the impulse to apologize for asserting herself. As she toured Minneapolis the night before, she said one of the main goals of the Lean In circles is to boost women’s confidence.

Toward the end of the visit to the circle at Brandt’s home, Carolyn Vreeman, also a Hennepin County employee, stood and quickly explained that what she’ll take away from the meeting is a commitment to engage more men in conversations about supporting the development of women leaders.

Brandt broke in, asking Vreeman to repeat herself, more slowly.

“I’m like super bossy, can you get up and do it one more time?” Brandt said.

Bossy is a word Sandberg says is too often applied to females, and rarely applied to males, so she seized the opportunity: “You’re not bossy!” she said. “You just have executive leadership skills.”

Sarah Borntrager, the high schooler who attended the second circle Sandberg visited, agrees that girls grow up with that bias. “We’re supposed to be seen as like meek, instead of assertive,” Borntrager said.

She said that attending a camp for Fire Explorers and seeing female leaders who weren’t afraid to stand up for themselves has helped her overcome that bias.

Sandberg thinks the work can start even earlier.

“The next time you see a little girl, and someone’s calling her bossy,” Sandberg said, “walk right up, big smile on your face and say, ‘That little girl’s not being bossy, that little girl has executive leadership skills.’ ”