DC Public Schools headquarters. (Marvin Joseph/The Washington Post)

Kaya Henderson was D.C. schools chancellor from 2010 to 2016.

Two weeks ago, DC Public Schools and the D.C. Public Charter School Board released student test results for the past school year. There was a tremendous amount to celebrate in the release. Across the board, student achievement is up. Students in nearly every grade, every subgroup and every subject area are showing improvement. I was excited to see that the percentage of students who are college- and career-ready is going up, and I was thrilled to see that the percentage of students scoring at the lowest levels on the test is going down. All of our students are showing incredible growth.

DCPS has now seen four consecutive years of growth in student outcomes in English and math. While there is still much work to be done, we should recognize the factors that have led to this consistent and broad-based improvement, even as DCPS has experienced district-level instability.

I believe three factors have led to continued student success.

First, DCPS has the highest-quality educators, including teachers, principals, librarians, counselors and paraprofessionals, that it has had in generations. This is true because, over the past decade, DCPS made enormous efforts to improve the quality of its workforce. DCPS developed and implemented IMPACT, a performance-evaluation tool that, research has shown, improved the quality of the educators. We also provided the best salaries in the region, hired better and more experienced teachers and principals and offered content-rich professional development opportunities. These changes caused some churn in the workforce, but replacing an ineffective or educator or one who is not onboard with the changes is positive churn. DCPS focused on increasing the effectiveness of its teaching staff so students have the opportunity to learn from the best educators possible.

Second, all DCPS students learned from the same rigorous, content-rich curriculum aligned to the Common Core standards and built with the help of our great educators. Starting in 2012, DCPS bucked the trend of devolving academic decisions to individual schools and focused on equity. We wanted all students to learn the same rigorous content no matter what school they went to or what Zip code they lived in. We wanted a student’s elementary school experience to serve her well no matter what DCPS middle school she went to. Once we built a model curriculum for schools, we built model lessons for every grade and subject. These lessons, called Cornerstones, made sure that all teachers had the chance to access amazing lesson plans that would advance student learning and help teachers maximize the potential in their students. You probably heard about second-graders learning to ride a bike in every school in the city. What you may have missed is that, while riding a bike was a fun and, for some students, a unique experience, it was only a small part of a broader lesson that helped students learn about their neighborhoods and maps. It was rigorous content mixed with a joyful experience.

Because all students had the chance to learn the same rigorous content and all teachers were exposed to great lessons, our students had a tremendous opportunity to succeed. That is what showed up in the recent test results.

I am convinced that our students performed well on their math and English tests because they got to enjoy music, dance, library, physical education, art and technology. Our high school students had access to more electives and more Advanced Placement classes than ever before — and more students took and scored well on AP tests than ever before. We didn’t stop there. We also offered field trips and study-abroad opportunities for hundreds of students. We showed that when school is a joyful place, learning comes more easily to everyone.

Finally, I believe school communities are more engaged with their schools. Though I don’t get the daily emails from parents anymore, I see how active they are on social media and how energized they are by their schools. It is these parents and community members who keep our schools moving forward while the city undergoes changes.

To me, the message is clear: We owe DCPS’s success to our great educators, the rigorous content they teach and the engaged communities around our schools. Because this message is clear, it is surprising to me to see people across the city who seek to undermine these crucial strategies. We must be careful not to kill the things that are leading to student success.

There has been a trend over the past decade to decentralize education decisions, to create portfolio districts and to emphasize autonomy. I understand the impulse, and I agree that some decisions are best made at the school level. But I also believe that when we devolve responsibilities down to individual schools, we are abdicating the responsibility of the district to ensure rigor and equity. No individual school could have created the curriculum, the model lessons or the teacher evaluation system that DCPS built. No one school can ensure that students in every ward have the chance to enjoy art and music classes. No amount of autonomy can ensure that every high school has AP classes.

I hope the DCPS results show that districts that put forth the hard work of nurturing great educators, designing rigorous content, and engaging students and families can produce real, broad and lasting results.