Kaya Henderson, chancellor of D.C. Public Schools, in August 2014. (Amanda Voisard/For The Washington Post)

When former D.C. schools chancellor Michelle A. Rhee resigned after the defeat of then-Mayor Adrian M. Fenty, her then-deputy, Kaya Henderson, had planned to follow her out the door.

But Rhee asked Henderson to stick with the city schools and continue the education reforms they began together. Vincent C. Gray, the newly elected Democratic mayor, asked her to stay, and she started getting calls from teachers and principals she had recruited.

“I tried to say ‘no’ a thousand different ways,” Henderson said in an interview this week, five years after she relented and took the reins of the city’s public schools. “Five years later, I am still having a good time and I am proud of what we have accomplished.”

The chancellor’s anniversary comes this month as the school system is celebrating signs of progress, including significant test-score gains, five consecutive years of enrollment increases after decades of declines and an uptick in graduation rates, ­to ­64 percent.

Unlike her predecessor, whose turbulent style and top-down approach made enemies of many teachers and politicians, Henderson is credited with taking a more collaborative approach. She also is praised for bringing a sustained focus to the work of digging the school system out of a deep hole and building what she described at an event this week at the National Press Club as a “halfway decent district.”

A Wonder Woman folder sits on Kaya Henderson’s desk in January 2011, when she was the interim chancellor of the D.C. Public Schools. (Matt McClain/The Washington Post)

Challenges remain vast, particularly in many of the lowest-performing schools, where academic growth has been incremental or stagnant and where the city’s most challenging students remain far behind their peers. But she hopes to build on momentum that has encouraged many people inside and outside the District.

“I think she has emerged as one of the most effective and popular school leaders any place in the country,” said Michael Casserly, executive director of the Council of the Great City Schools. “She is improving the D.C. Public Schools in ways that everybody is trying to do with their own cities.”

Henderson and the schools have benefited from the city’s expanding economic base, a growing population of school-age children and some of the highest per-pupil funding in the country. With mayoral control, the chancellor has wide latitude to experiment and make major changes, and her approach appears to be meeting with some success.

Two weeks ago, the school system posted significant gains on the National Assessment of Educational Progress, a closely watched measure of student achievement. Scores for fourth-graders in the school system climbed four points on the national math test between 2013 and 2015 and eight points on the reading test — the largest jump of any urban district. In 2007, D.C. schools’ fourth-grade scores ranked at the bottom of large urban districts participating in the test; this year, they are in the middle. Eighth-grade scores are still near the bottom.

U.S. Education Secretary Arne Duncan pointed to the city’s success, saying after the data was released that the educators, students and leaders of D.C. schools “deserve the gratitude of this country” for their hard work. Broader improvements in the school system also have won praise from President Obama.

Despite the accolades, many educators and advocates are concerned that progress in the school system is still not being felt by many of city’s most disadvantaged students. In many schools in the poorest parts of the city, less than a third of students perform on grade level, standardized tests show.

A National Research Council report released in June found that more than seven years after a series of reforms took root — when Fenty took control of the city’s schools and appointed Rhee as chancellor — the District’s poor and minority students are still far less likely than their peers to have a quality teacher in their classrooms, perform at grade level and graduate from high school in four years.

Although performance on standardized tests has improved for all groups, the city’s academic achievement gap remains stark. The report urged the city to make addressing disparities its primary objective.

The recent success on NAEP overshadowed sobering results released a day earlier from new standardized tests tied to the Common Core State Standards. None of the test takers at seven of the city’s comprehensive high schools scored well enough to be considered “college ready” on a geometry test.

This year, the chancellor funneled millions of additional dollars into the city’s neighborhood high schools to add more elective and college-level courses, an effort to enhance scant offerings and boost low enrollments.

Cathy Reilly, executive director of the Senior High Alliance of Parents, Principals and Educators, said the investments are welcome but she is concerned that some decisions during the past seven years, including closing middle schools that feed into high schools and focusing on magnet schools, have made it more difficult for comprehensive high schools to compete for students in a system where 44 percent of public school students opt to leave the system for charter schools. “There is still a lot of work to do,” she said.

Henderson said she plans to redouble efforts this year in all of the District’s lowest-performing schools by extending learning time, refining professional development and supporting families in new ways.

Many attribute a large measure of the system’s progress to Henderson’s longevity. Urban school superintendents, on average, leave after about three years, according to a survey by the Council of the Great City Schools — a reflection of bruising city politics and intense pressure for instant success.

In the decade before Rhee was appointed chancellor, the District’s schools were led by six superintendents, bringing a succession of strategic plans and funding formulas.

“The government often thinks the path to improvement is to fire people, without recognizing that firing people often means starting over,” said D.C. Council Chairman Phil Mendelson (D). “Historically, that has just perpetuated enormous instability in the school system.”

Henderson, building on Rhee’s work, has been able to carry out a more methodical and consistent approach, with new academic standards and related instructional materials, professional development, coaching and programs.

“She brings some continuity,” Mendelson said. “She has a vision, and she is pursuing it.”

Although the system as a whole is benefiting from more stability, many educators and parents say that instability remains a problem at the school level.

One in four D.C. schools started the school year with a new principal. Some retired or were promoted, and others were fired. Evaluations for teachers and principals can yield generous raises for high performers and trigger termination for low performers.

Walter Pennington, a father of twins in pre-kindergarten at Payne Elementary on Capitol Hill, helped wage a campaign to have its principal, Vielka Scott-Marcus, reappointed after learning last spring she would be leaving.

He said Scott-Marcus was making improvements at Payne, increasing enrollment and making it feel like a neighborhood school — no small task in a community with million-dollar homes and a family homeless shelter.

This year, they are starting over with an interim principal. “It feels like a throwaway year,” Pennington said.

Henderson said that the school system is “redefining what quality means in the educator workforce,” a process that is bound to lead to churn.

She said the school system is training principals who get up to speed quickly in new schools. And she noted that there is a 92 percent retention rate among teachers who are rated highly effective.

Turnover has been a flash point with the Washington Teachers’ Union, which is concerned that the evaluations are not fair and overly punitive. Half of the teachers in affluent Ward 3 were considered highly effective in 2013-2014, while just under 20 percent of teachers working in high-poverty schools in Wards 7 and 8 received the highest rating.

Randi Weingarten, president of the American Federation of Teachers, helped negotiate final terms of the teachers contract in 2010 with D.C. schools and said she found Henderson to be calm and collegial. Since then, she has been disappointed to see there is not more collaboration with the union in addressing such concerns.

There continues to be an “us versus them” mentality, Weingarten said.

Despite the politics and the challenges in the work, Henderson frequently tells people that she has the best job in the city.

She plans to stay in her role until at least 2017, when she intends to check her progress against a set of goals she has set for the schools.

“I have to ask, ‘Am I the right person to continue to lead this organization?’ ” she said. She does not know what the answer will be, but she said the deadline helps to motivate her.

“If I am going to leave in 2017, that’s right around the corner,” she said. “I have a lot of stuff to get done.”