James Cavanagh is 22 years old, fresh out of the University of Delaware. With his degree in elementary education, he could have gotten a job anywhere—and he chose to teach at one of the most demanding public schools in America.

His college buddies were hired at schools with mid-afternoon dismissals and two and a half months of summer vacation. For not much more pay, Cavanagh worked nearly all of August and this fall is putting in 12-hour days, plus attending graduate school.

In exchange, he gets to be a part of one of the nation’s top charter schools, North Star Academy in Newark, where poor, minority students routinely outperform their peers in wealthier ZIP codes on standardized tests. And he’s getting extensive support designed to make him both effective and eager to stick around.

A small but influential group of schools like North Star, dubbed "no excuses" charters because of their high behavioral and academic expectations, has proven that, with very hard work by students and staff, the country’s crippling achievement gap is possible to narrow or even close. These schools helped inspire a national push to give struggling students more time in school.

But success created a different challenge: how to keep teachers from burning out and leaving.

Since the "no excuses" movement began in the mid-1990s, its schools developed a reputation for attracting teachers who are young, idealistic and often white, available to families around the clock until they leave after a few years. Sometimes they’re ready to have children of their own or move on to more lucrative career prospects; other times they’re just tired. The phenomenon has been blasted for depriving students of stable adult relationships and creating mistrust in minority neighborhoods when white teachers serving black and Hispanic students come and go.

So now the focus is sustainability. The Knowledge Is Power Program (KIPP), which opened the first two "no excuses" schools in 1995 and is now the nation’s largest charter chain, is offering on-site daycare for teachers working long hours in some locations.

YES Prep, a network of 13 charters in Houston that has been recognized as among the nation’s top performing, ensures students get quality experiences outside of the classroom. Rather than keeping students at their desks all year, YES Prep schools connect them with the types of summer camps, wilderness expeditions and international travel opportunities enjoyed by their middle class peers—building character while giving teachers a break and getting parents into the mindset they’ll eventually need to send their children off to college.

At Uncommon Schools, the parent organization that operates 10 North Star schools in Newark as well as more than 30 other schools in cities including New York and Boston, there is a heavy emphasis on training and mentoring teachers, and newbies like Cavanagh often get a lighter class load their first year. Diversity initiatives are attracting more minority candidates, often with a dedication to give back to their own communities, as well as veteran teachers from other schools and career changers. "When we first started, folks were working all day, on the weekends," said Brett Peiser, Uncommon’s CEO. Today, he said, teachers are told in no uncertain terms that, "We want you to go home. We want you to balance your life."

"No excuses" schools are a fraction of all charters, public schools that operate independently, but their numbers are growing every year and they are closely watched because of their successes in raising test scores and getting historically underserved students to college.

The predicament they wrestle with is universal: Kids who are behind academically need a lot of time to catch up. But time in school means nothing if it’s not high quality, so teachers also need time for training and collaboration—and they need time to decompress outside work.

James Cavanagh helps one of his fifth-grade math students at North Star Academy’s Downtown Middle School. (Sara Neufeld)

At regular public schools where scheduling is dictated by union contracts, turnover in impoverished neighborhoods also tends to be high as teachers with less guidance are overwhelmed by the demands of their jobs. Uncommon Schools’ turnover is comparable to the national urban average, with about 20 percent of teachers leaving annually, an improvement from earlier years.

Cavanagh, a Long Island native who teaches fifth-grade math at North Star’s Downtown Middle School campus in Newark, spent three weeks there preparing before students’ Aug. 25 arrival, versus the standard two days of preparation time that most of his friends got. That allowed him to start the year with confidence.

"It’s all meaningful time and time I would be spending at home anyway … especially as a 22-year-old first-year teacher," said Cavanagh, who traded jeans, sneakers and day-old stubble for a tie and a neat beard as the school year began. He hopes to go into education policy someday but plans to spend many years in the classroom first.

Not long ago, Daniel Zane Johnson had similar optimism starting a job teaching seventh-grade science at Endeavor Middle School, a "no excuses" charter in Brooklyn run by the high-performing network Achievement First. Like Cavanagh, he was grateful for extensive support and preparation time. But after two years putting in 11-hour days at school and then taking work home, he felt too tired to offer students his best. He quit in June and now works in client services for an education software company.

"There’s a general sense of fatigue that sets in, and it’s very hard to fight," said Johnson, now 26. "When you’re working in a very demanding environment, even if you are extremely passionate, you still get a mental and physical fatigue, and it affects your attitude … When you’re a teacher, your job is standing in front of kids for six hours of your day. That can be very difficult and very stressful when you’re feeling worn out."

Jason Bernal knows exhaustion well. Sixteen years ago, he was a young Spanish teacher working at a new startup charter middle and high school in Houston, part of a team determined not to waste a moment in helping students escape the vicious cycle of poverty. Kids came from all over town, and bus routes began at 5:45 a.m. to get everyone to school by 7:30. So eager was Bernal to make a great education accessible to underserved students that he drove a 15-passenger van himself. The school day ran some days until 5 p.m., and students who hadn’t completed their homework had to stay until 6:30.

"It was kind of survival of the fittest," Bernal recalled. Unable to keep up with the pace, teachers and students left in large numbers.

The school where Bernal worked is now the flagship campus for YES Prep. Bernal is the CEO, and now as the father of two young children, he’s come to realize the importance of setting a sustainable pace for the organization. YES Prep has developed hierarchies within its teaching and administrative ranks to give an ambitious staff room to advance without leaving the profession. The school year is now the usual American 180 days—down from more than 190—Saturday school is at principals’ discretion, and classes dismiss early once a week for teacher training.

But four days a week, the school day is still 7:30 a.m. to 4 p.m., about two hours longer than the national average. Some things have changed, but students’ extensive needs have not.

* * *

Among education advocates, controversy rages over the significance of teacher turnover. Studies suggest that turnover can harm student achievement and disrupt a school culture generally.

But if some of the nation’s best and brightest are willing to give their all for a few years and produce good results, does it really matter if they don’t want to make teaching a lifetime career? Teach For America, which in 1990 began placing college graduates for two years in high-needs schools, many of them now charters, argues that the benefits outweigh the drawbacks. Besides, the program says its participants return for a second year of teaching at higher rates than their peers elsewhere and points out that nearly half of all teachers nationally leave the classroom within five years.

Stacie Kurtz saw both sides of the debate during her six years teaching English at Endeavor Middle School in Brooklyn. She said the amount of academic progress students make there "is just astounding."

"It is definitely because of how much time they get, but it’s also because of the quality of instruction," said Kurtz, who left in June and now works for another charter in a job supporting other teachers. But she was sad to see students acting like they didn’t care when teachers quit, a bit like the thick skin they try to display after repeatedly witnessing neighborhood violence. "They’re just like, ‘Oh, everybody leaves,’" she said. At 36, she calls herself "an old lady of the charter world."

A few miles southeast of Endeavor, Janna Genzlinger was determined to reduce teacher turnover last year when she became the director of Brooklyn Ascend Charter School’s elementary campus. The year prior, 42 percent of teachers had left.

"If we don’t retain our teachers, our students suffer," said Genzlinger, who was a veteran of the Uncommon Schools network before she came to Ascend Learning. Ascend does not ascribe to the strict student disciplinary codes of "no excuses" charters but also has created a culture of high expectations with a young staff at its seven Brooklyn schools.

Genzlinger began asking her teachers what she could do to make their lives easier. She found them deeply appreciative of small things, like hiring a babysitter to watch their young children during back-to-school night and covering their early classes the morning after a late school concert. This year, the school kept 91 percent of its teachers.

In other efforts to reduce turnover, Ascend schools this year reduced the length of their regular academic day by 45 minutes, to eight hours, while giving teachers a raise. Elementary students are now selectively targeted to stay late for small group instruction. Middle school students stay for homework help from local college students, followed by enrichment activities such as karate, dance and African drumming that are typically led by community members and partner organizations so teachers can go home.

Yet even with administrators urging them to take a break, teachers often do not when confronted with tremendous student needs. "A lot of people will grudgingly admit that we as teachers are our own worst enemy in terms of burning ourselves out," said Henry Seton, a humanities teacher in Massachusetts at the Community Charter School of Cambridge, which has been increasing its support for teachers while maintaining moderate hours. "We’re so eager to serve."

* * *

The North Star schools, named after Frederick Douglass’s abolitionist newspaper The North Star and for the North Star’s historic depiction as a symbol of freedom, are collectively among the most celebrated charters in the country. They draw visitors from around the world, and their practices are featured in two books that have become required reading in many urban schools: Teach Like A Champion and Driven By Data, both written by Uncommon Schools employees.

Steps from the Newark Museum and the New Jersey Performing Arts Center, Downtown Middle School occupies a three-story converted bank attached to a gleaming new 52,000 square-foot building housing North Star College Preparatory Academy High School. The instructional day runs Monday through Thursday from 7:45 a.m. until 3:30 p.m. (classes dismiss early on Fridays for teacher training). But most of the 308 students, 98 percent of whom are black and Hispanic, are there considerably longer.

Tutoring begins at 7 a.m., and showing up for a "brain breakfast" of food and drills at 7:15 a.m. earns a child two "North Star dollars." Every student begins the week with $50 of fake money, and dollars are deducted for infractions such as not completing homework and not paying attention in class. Anyone whose paycheck falls below $35 has to stay after school until 5 p.m. Many stay anyway for extracurricular activities like flag football, step-dancing and art.

Kamron Oglive, a sixth-grader at Brooklyn Ascend Charter School, participates in the African drumming orchestra after school. (Sara Neufeld)

As a new teacher, Cavanagh is struck not so much by the quantity of time students and staff spend at school—that he’d been warned about—as he is by the intensity. Every moment is planned. No moment is wasted, and no one ever forgets why they are there: to get students who typically come in years behind on track for college.

Before the first day of school, a week before other Newark schools began, Cavanagh had done more than a dozen trial runs of his first-day lesson on multiplication and place value. He had gotten feedback on the lesson plan from a veteran colleague, who advised him on everything from how to be stern if a child leaves an answer blank to how to get the class to pass out papers in 15 seconds or less. (One tip: Instruct students to pass their papers "from the wall to the door" rather than "from right to left" so anxious new middle-schoolers don’t need to pause to make the right-left distinction.)

His colleagues have offered extensive tips on time management. Thanks to one, Cavanagh bought a numerical keypad to attach to his laptop while entering student grades; by reaching the number keys faster, he’s saving 20 minutes a night. He shaved off a minute from the time it takes students to enter his classroom and get seated by leaning forward when he shakes their hands at the door. For every class assignment, he puts a timer on the overhead projector; he tried once teaching without it and found keeping students on task was far harder.

Cavanagh rises at 5:30 each morning and dashes out of his apartment in Nutley, N.J., to arrive at school by 6:15 a.m. Although he doesn’t run any after-school activities—new teachers are advised against doing so—he doesn’t usually go home until 6:30 p.m., when the building shuts down. On Monday nights and Saturdays, he’s in classes at the Relay Graduate School of Education, a graduate school founded by leaders in the "no excuses" charter movement to share practices and develop a steady pipeline of teachers. (The president of Relay, Norman Atkins, co-founded North Star.)

A reprieve is coming for Cavanagh soon, though, when another fifth-grade math teacher returns from maternity leave this month. He will go from teaching three 1.5-hour classes a day to one class and spend the other periods working with students individually and in small groups. This is part of a deliberate strategy at a growing number of charter networks to ease new teachers into an intense schedule.

The hours are an adjustment for the students, too. Long school days are generally attractive to parents, who have made North Star schools the most sought-after in Newark, but they can be a tough sell for pre-teens and teenagers.

"It makes them not want to come here," said Pavel Annor, 10, a pensive fifth-grader who came from a struggling neighborhood elementary school and participates in the robotics club. He said he was surprised to discover that the day at Downtown Middle actually feels shorter than it did at his old school because classes are more interesting. Students have at least two hours a day in English and an hour and a half in math, but that time is balanced with a daily "special" like art, music or gym, as well as a morning period for character development. At his old school, Pavel said, "we hardly had science and extra stuff like gym and music."

Eighth-grader Nashir Taylor, 13, said it’s hard coming home later than his friends in the neighborhood and seeing them outside playing basketball when he has homework to do, but he knows his efforts will pay off someday. "Most people are lazy and don’t realize the benefits of education," he said.

One of Cavanagh’s mentor teachers, Clarence McNeil, likes to tell the story of the first time he heard about North Star. One summer day, he was riding the public bus up a rough street, South Orange Avenue, and he saw a few of the network’s students being picked on because they had to attend summer school. "One of the kids said, ‘I’d rather go to school all year at my school than have summers off at yours because I’m going to college.’ I thought it was the most incredible thing I ever heard a kid say," said McNeil, 49, a former defense attorney who made a mid-career switch to teaching after realizing he was coming to the game too late to make a difference for young men of color.

McNeil has now been teaching at Downtown Middle for a decade, making him one of the school’s most senior staff members. He has six kids at home but puts in longer hours than just about anyone, beginning with a 4 a.m. alarm.

"I have to be here because the amount of time that we spend on this is absolutely necessary. We’re at war," he said. "The achievement gap is very real, and it’s killing my people."

He gets frustrated by the suggestion that days are too long, saying that he has yet to see efforts come close to being counterproductive, and the hours he and his colleagues put in still are not nearly enough.

How much time would it take, then?

"See, that’s the problem," he said. "I’d like us to exhaust ourselves and find out."

This story was produced in collaboration with The Hechinger Report.