The night Mike Mann faced a roomful of angry parents, he was a 40-year-old former history and English teacher who had built a splendid reputation as principal of a charter middle school in Newark full of students from low-income families.

He had just been named principal of the high school that was part of the same charter network. He quickly made many drastic changes. That was why he was in such trouble.

He would survive. The school would prosper. But only because Mann worked for weeks to convince families that their children were able to accomplish more than they had previously been asked to do. Critics have long suggested that charter schools work only because their parents are so supportive, but what happened at Mann’s campus suggests this is a misreading of what makes such schools succeed.

The first school in what is now called the Uncommon Schools network was North Star Academy, a middle school created in 1997 by journalist and entrepreneur Norman Atkins and community school principal Jamey Verrilli. The two men, who also taught, challenged students so well they produced the second-highest state test scores in Newark in their first year.

Mann was one of their stars, a creative teacher who also ran a soccer league. When he led Uncommon’s second middle school, he thought his first graduating class of eighth-graders was so strong that the network’s small high school could be even more rigorous than it had been designed to be.

It was better than the average Newark high school, Mann thought, but he wanted to raise the bar higher for the incoming ninth-grade class. “Selfishly I had poured my heart and soul into them,” he told me. He thought they could be successful at a high school that demanded much more.

He took over the high school in 2009 with two co-founders of his middle school. The three of them talked at length with the high school faculty. They described their plans to create standards much tougher than those that had been set by individual teachers. Some instructors much loved by families resigned as a result.

Several parents and students vigorously protested the change. Mann was told he had trashed the heart and soul of North Star Academy high school.

Among Mann’s many responses to the crisis was to schedule a showing for everyone of the 2000 film “Remember the Titans.” It starred Denzel Washington as a high school football coach who brought new discipline to a team. The previous coach had had 10 straight winning seasons. “That’s very impressive,” the new coach said, but “winning is just one more better than breaking even.” He wanted a state championship.

As a soccer coach, Mann knew the power of sports metaphors. The movie was about high expectations, no compromises and hard work. At North Star, if students were skipping their homework or shunning other school values, they were reminded they were hurting their own and their peers’ chances of going to college. They had to turn in their homework first thing in the morning. If they hadn’t done it, or done it poorly, they would know by 11 a.m. that they would be staying after school to do it right.

Mann and his team created enhanced lessons for each class. Data about whether students learned or didn’t learn drove the teaching. Instructional coaches observed teachers each week to help them improve their skills.

There were still complaints. At one meeting with protesting parents, Mann said something extraordinary for a principal. “I am just not reducing the standards or the expectations, and you can’t work on this as long as I can,” he said. “You all have jobs. You can work on this maybe an hour or two a day, whereas I am working on this for 10 hours a day every day.”

If the theory was correct that charters are good only because of automatic family support, with the best parents choosing charters over regular public schools, Mann would have had to give up. Instead he won because of a key feature of charters. The school was independent of the public school district. The charter’s board, which included two parents, was not answerable to voters. The school could survive as long as enough students signed up. At a regular public high school, faced with such political pressure by parents, Mann would probably have been told to junk his plan or be fired.

The night Mann vowed he would never give up, he went home exhausted. He had one recurring thought: His life sucked. He had to teach his research methods class for seniors the next morning. Some had watched their parents pummel him the night before.

But the class went fine. His students may have hated him as a school leader but liked him as a teacher. In class he was not the cruel dictator destroying their school. By the third month, the resistance had faded away.

Mann is still principal of the school, now known as North Star Academy Washington Park High School in the Uncommon system. It has become one of very few predominantly low-income schools in the country whose Advanced Placement test passing rates match affluent suburban schools. Its participation rate on AP exams is in the top 1 percent of all U.S. schools.

This year, four days after Mann’s school closed in mid-March because of the pandemic, he opened an online version of the school with a video of him sharing the screen with a slide show. The first slide said: “When Life Gives You Lemons, Make Lemonade.” Each class for each subject is an hour. Attendance has averaged 93 percent, about what it was before the school closed.

Parents, as usual, have embraced the hard work by their children. Next week, I will show how the Uncommon system works from the perspective of a teacher who has been there 15 years.