At a Henderson middle school, mistakes are not only acceptable — they’re welcomed.

The mindset may shock the system of over-achievers who can’t fathom the thought of a less-than-stellar athletic performance, imperfect musical routine or any grade less than an “A.” But Nicole Donadio, principal of Bob Miller Middle School, considers these adolescent challenges valuable learning moments that will pay dividends down the road.

“It’s all tied back to the idea that it’s OK to fail,” she said. “It’s what are you going to do to show your tenacity and resilience?”

Those vocabulary words ring familiar to students in this five-star middle school, where character education has taken up residence alongside science, language arts and math. A sixth-grade classroom features student-designed illustrations representing character traits such as grit and resilience. In another wing of the building, a “Star Wars”-themed poster reminds students the differences between a growth mindset versus a fixed mindset — the former being more desirable because it describes a person who embraces challenges, learns from criticism and remains open to new things.

Last month, character development guru Angela Duckworth, author of the New York Times bestseller “Grit: The Power and Passion of Perseverance,” paid the school a visit. Wearing a navy blue skirt and sneakers, Duckworth addressed a gymnasium full of middle schoolers prone to giggles at the mere mention of their changing bodies and hormones. But Duckworth’s message was about the adolescent brain and, more specifically, the “exciting development” happening in that organ.

“So if it feels like you have a lot going on, it’s true,” she said.

She then turned to those character traits Bob Miller teachers have been weaving into lessons. The scientist-turned-author said grit, which she describes as a combination of passion and perseverance, helped see her book through fruition. Simply put, she didn’t give up even when the project left her in tears some days.

Duckworth implored Bob Miller students to see growth as part of human nature, failings and all.

The Clark County School District is partnering with a research network associated with Character Lab, the nonprofit founded by Duckworth and two educators that aims to bridge the gap between character-related science discoveries and the education world. The end goal is to bring more character development strategies to the classroom.

Next academic year, seven to 10 schools in Clark County will join the research network, which means students will participate in various character-building lessons and researchers will study the results, said Kellie Ballard, a director in the deputy superintendent’s office. More details, including which schools will be participate, have not been finalized.

The no-cost partnership, Ballard said, aligns with the district’s increasing focus on social-emotional learning. Some schools already teach their students about growth mindset.

“It’s certainly not going to be completely out of the blue,” Ballard said. “Principals are champing at the bit to get started.”

While schools are hubs for practice and progress, they’re not always seen as friendly to failure. And in the grand scheme of personal development, that can be a problem, said Alaine Tingey, a seventh-grade science teacher at Bob Miller Middle School.

“Sometimes we learn more in the failure than getting it right,” she said. “That’s a struggle when we feel like kids are just chasing a grade or trying to get their parents off their back.”

Bob Miller staff have made it a point to create challenging learning environments, pushing students to that uncomfortable zone that requires trial and error and — you guessed it — tenacity and resilience. Earlier this month, the school’s three-year-old Science Olympiad team took first place in the state, beating a host of magnet and charter schools. Tingey says the experience instilled these character traits among participating students, who persevered with a fledgling team while competing against more experienced ones.

Over time, their struggles paid off.

But Tingey said winning was just a fortunate byproduct of a learning experience filled with obstacles and hard work —in other words, a journey that stands to benefit students more than a first-place medal.

“We’ve tried to smooth things over so much for kids that they don’t struggle,” she said. “They don’t know how to deal with adversity.”

Sixth-grade teacher Jaime Huggins, who teaches English language arts, said she suffered from a fixed mindset as a student. She let fear stop her from doing things that seemed insurmountable. Now, as the person leading the classroom, Huggins has embraced this type of character education, which she said helps build the “whole student” as opposed to just the academic side of their brain.

She’s integrating Character Lab lessons, most of which revolve around self-reflection, into her curriculum about once a week. For instance, Huggins recently asked students to read a list of values, circle three they deem most important and then explain why.

“The ones that usually tend to get frustrated have taken a step back and not gotten so frustrated,” she said. “They’re embracing that challenge a bit more.”

Her students agree. The newly minted middle schoolers rattled off a list of stressors — changing classes every period, keeping track of assignments, feeling a sense of competition socially and academically.

Abigail Haggerty said the messages about positive thinking and determination have proved especially helpful when she’s learning difficult math concepts.

“Don’t just rely on what you can do,” she said. “Rely on how smart you are.”

Her classmate, Susanne Massa, put it this way: “Growth mindset is, ‘I may not be good at this now, but I can get better at it.’”

It’s an attitude the school’s educators hope their students carry with them throughout life.