Last month marked the 20th anniversary of the day I found Susan Schaeffler, then 31 years old, working in an Anacostia church basement where she was about to open a public charter middle school for mostly impoverished students. She and her father were developing blisters as they assembled student desks and chairs.

She said she was starting with just fifth-graders. She would call them “The Class of 2009.” “Oh, I get it,” her father said. “That’s the year they will graduate from high school.”

“No, Dad,” she said. “That’s the year they are going to college.”

Such big plans seemed to me bound to fail. But when I checked in 2009, Schaeffler was not far from her goal. Fifty-eight of the 62 children who made it through eighth grade at what is still called the KIPP DC KEY Academy middle school had completed high school and were going to college.

By that time Schaeffler had opened many more schools. As the chief executive of KIPP DC, she now leads 20 schools with 7,300 students from preschool through high school. That is 7 percent of the D.C. public school population. Her team has established high standards for learning that have drawn strong support from D.C. families, while evolving from a focus on just college to a promise to help students achieve successful careers — what KIPP calls “choice-filled lives”— by whatever paths they select.

Schaeffler has overseen the education of more than 20,000 children in two decades. She is the longest-serving regional director among KIPP’s 28 regions, 270 schools and 120,000 students. KIPP is the largest network in the country of tax-supported but privately run charter schools.

“It’s pretty simple,” Schaeffler said. “I love the work.” She and her team have deepened the recruitment and training of teachers. They have made adjustments to the teaching of children with learning disabilities and provided mental health support. KIPP students returned to classrooms last week, except for those enrolled in an online program, created by Schaeffler’s team, for up to 280 students who for now would do better learning at home.

Her success in the District almost didn’t happen. KIPP was created in a Houston classroom in 1994 by two teachers in their mid-20s, Mike Feinberg and Dave Levin. They had learned from two mentors the power of imagination, fun, compassion, order and depth in an inner-city school. After five years they had raised achievement so high at two middle schools in Houston and the South Bronx that “60 Minutes” did a story. The founders of the Gap stores offered them $15 million to open more KIPPs (originally an acronym for the Knowledge Is Power Program).

The KIPP co-founders wanted at least one of the new schools to be in Atlanta. Georgia’s governor was begging for it.

Schaeffler had become a teacher in Baltimore right out of college through the Teach For America program. She then moved to a D.C. school with a splendid principal. She was famously gregarious. The Teach For America grapevine knew her well.

The KIPP co-founders were impressed. They said she could start the first KIPP school in Atlanta. She said no. Her friends and family were in D.C. She told them she would start the school there, or not at all. Admiring such nerve, they said yes.

Ask Schaeffler what her biggest problems are now, and she will cite the intense competition for teaching talent. She and her team have created the Capital Teaching Residency, which hires young people — with an emphasis on minorities — to work as classroom aides and be mentored by experienced teachers. Since 2009, KIPP DC has trained more than 600 educators. Seventy-four percent of the CTR corps members identify as people of color. A quarter of KIPP DC principals started in the CTR.

Schaeffler’s energy and KIPP’s reputation have attracted to its board some of the city’s most knowledgeable education fundraisers. KIPP DC will soon complete a second high school campus at a cost of $90 million. It will also include a recreation center for the neighborhood and space for people working on community projects.

The key change from 20 years ago is that KIPP DC students start much sooner than fifth grade, so their teachers’ emphasis on hard work, attention and cooperation is not something they have to adjust to suddenly when they are 10. Achievement rates have remained high. KIPP DC’s College Preparatory high school has an Advanced Placement test participation rate in the top 9 percent for all U.S. schools.

In recent years, Schaeffler and other KIPP leaders have focused more on KIPP alumni, including an expanded program called KIPP Forward to support graduates through college, career and beyond.

Schaeffler’s success comes from a mix of brilliance, charm and single-mindedness. She has been an icon in the charter movement for a long time. She has also been lucky to work in a city where the regular school district has cooperated with charter schools, not a common occurrence.

KIPP has been called dull and oppressive by anti-charter critics, but that is hard to square with the creative teaching, music, art and games you see if you visit any of their schools.

Great administrators make great schools. Schaeffler’s time at KIPP DC shows how far American education can go if imaginative people are given a chance to build programs and establish relationships that can stimulate innovation and growth for decades.