PHOENIX — The fathers leaned over the chain-link fence and intently watched the junior-high football coach at Mesa Preparatory Academy.

Some of the dads were anxious. Others were fearful. Many of their sons were playing football for the first time. They didn’t know how to put on shoulder pads. They weren’t sure how to buckle their helmets. Heck, some of them didn’t even know how to do a jumping jack.

To make matters worse, there was the coach. Greg Staloch thought about the phone call he had received from his wife, Chris, while he was on a business trip. She told him about the introductory meeting with the new coach and how excited their son, Nick, was to be playing football.

Then she gave him the bad news. The head coach was a woman. So was her lone assistant.

That’s why Staloch was here, with the other fathers — to see for themselves why Mesa Prep would bring a woman into a man’s world.

“To say I was skeptical is probably kind,” Staloch recalled. “My guts told me this was going to be a failed experiment.”

Staloch stayed for the entire workout. When it was over, his skepticism had been swept aside by shame and embarrassment.

“It’s hard to articulate the emotional event you have when you go in with flat-out sexist thinking and realize just how wrong you can be about something,” he said. “She clearly understood the game, and the kids responded to her. I gotta tell you, it changed my beliefs.”

Two years have passed since that late-summer afternoon in 2008. The coach, Amy Arnold, is now the varsity football coach at Mesa Prep, a Class 1A charter school that plays eight-man football. She has two assistants, both women, making Mesa Prep the only school in the country to have an all-female coaching staff.

But the players and parents at Mesa Prep no longer see Arnold through the prism of gender. She is what she’s always wanted to be: Coach Amy.

The National Federation of State High School Associations does not keep gender-based statistics but Arnold, 38, is believed to be one of only two female high-school head football coaches in the country.

Arnold, however, doesn’t see herself as a trailblazer. Coaching is simply the latest evolution of her love for football.

A self-admitted tomboy, Arnold spent much of her youth in Oklahoma and Kansas playing sports with the neighborhood boys. From 2002 to 2007, she was a lineman — “A-Bomb Arnold” — for the Arizona Caliente of the Women’s Professional Football League and the Phoenix Prowlers of the Women’s Football Alliance. Arnold heard of the Mesa Prep opening soon after the school opened in February 2008. She knew she would be a long shot for the job. She had no coaching experience, and, of course, she was a she.

Mesa Prep was not handcuffed by society’s norms, though. The Great Hearts Academy school, which provides a liberal-arts education and has just 321 students, emphasizes academics over athletics.

So when no one on the faculty volunteered to coach the junior-high team, then-athletic director Jean-Mark O’Connor decided to think outside the gender box. He sent an e-mail to Prowlers’ owner Bryant Sewall, asking if there was anyone on his team he’d recommend as a coach.

Less than two days later, Arnold was in O’Connor’s office for an interview.

“I knew in the first 10 minutes I had found the right person,” O’Connor said. “She was extremely knowledgeable and very passionate. She was very concerned about doing things right from a sportsmanship standpoint, from an ethical standpoint and from an attitude standpoint. I knew right then she would be a very good coach.”

Some Mesa Prep parents didn’t share his enthusiasm. O’Connor said a few fathers came up to him privately and said, in essence, “We’re sure you know what you’re doing, but do you know what you’re doing?” Into this culture of skepticism stepped Arnold, who raised more eyebrows when she hired former Caliente teammate Kim Hoke as her only assistant. The women set out to build a football team. First, however, they had to convince the Monsoons players — and their parents — that they weren’t a novelty act.

“There were some kids talking about it,” said quarterback Cameron Labban, then a seventh-grader. “They were like, ‘We’re going to be coached by a girl?’ ”

Like Staloch, many of the parents harbored preconceived notions about women and football. They wondered if she knew the game and could command respect from her players.

“I honestly don’t think there’s a lot of room for femininity in coaching football,” Arnold said. “A woman, yes. But passive? No. I try very hard to stay away from that.”

When a couple of fathers tried to challenge Arnold’s knowledge or question her coaching methods, she put them in their place. By the end of the first week, she had won over her doubters.

“Immediately the boys responded to them (the coaches) with the utmost respect,” said Labban’s mother, Diane. “And the rest of us could see Amy’s ability. My husband knows football but not the way Amy knows football.”

No one expected the team to excel, not with a new coach and a bunch of kids who had never played the game. Staloch remembers watching the first practice and thinking, “Oh God, they’re going to get killed.”

Yet Mesa Prep won the Great Hearts Academies middle-school championship. It was the Bad News Bears in shoulder pads, and when Karen Bryson, one of Arnold’s professors at Ottawa University heard the story — Arnold is completing her bachelor’s degree in education — she thought it could be turned into a movie.

Bryson and Arnold co-wrote the script, and it recently was optioned by Hollywood producer Victoria Slater, who is pitching it to studios.

Arnold has done more than win football games at Mesa Prep; she’s changed how Mesa Prep’s players and parents view a woman’s abilities.

The players who were initially skeptical of Arnold now look upon her hiring as a moment of enlightenment.

“I’m actually kind of proud of it,” Labban said. “I remember back in seventh grade, looking at all the coaches on the other sideline and sort of thinking, ‘Well, look at our coaches.’”

Staloch has thought back to when he was a teenager, a Midwestern farm boy who believed women had their place — and it wasn’t on a football field. He held those views for much of his life, until the moment Arnold blew her whistle and showed him that there can be equality in sports, too.

“I held a lot of biases, and I’m ashamed of those original emotions,” he said. “I’m so glad that because of Coach, my son certainly doesn’t harbor the views I harbored as a 15-year-old.”

Arnold is skeptical her success will open doors for other female coaches. One reason: Because so few women play football and understand the game at a high level, there are fewer qualified coaching candidates to choose from.

“I think a huge school like a Hamilton would face an inordinate amount of public outcry if it hired a female coach,” O’Connor said. “What it takes is courage, even at a small and unknown school as Mesa Prep, and the commitment to do the right thing. The courage in this case was to find the very best coach available and that’s what we did.”

For that, Arnold always will be grateful.

“A woman can become a student of the game just as easily as a man,” she said. “I’ve proven I can coach.”