Mayor Vincent Gray surprised Julia King in her classroom last week with the news that she had been named the city’s teacher of the year.

Teacher Julia King works with students. Photo courtesy D.C. Prep.

A morning math lesson hadn’t gone as well as she’d hoped. It could have been more rigorous, could have better nudged students to think on their own. “I was really hard on myself, just feeling really disappointed,” King said.

She set about redesigning the lesson for her afternoon students, wholesale rethinking her teaching strategy. The revamped version was a success.

That kind of drive and relentless self-reflection are just part of what makes King an outstanding educator, school officials say.

“She is a passionate and infinitely creative and inspiring teacher,” said Cassie Pergament, principal of D.C. Prep’s Edgewood middle school campus, which serves primarily poor and minority children.

King pushes students not just to achieve academically but also to be “great citizens of the world,” Pergament said.

King was selected for the award from a group of nominees that included teachers at public charter schools as well as D.C. public schools. Other finalists were Laura Good of Excel Academy, an all-girls charter school, and Shajena Erazo of Ballou Senior High School.

King decided she wanted to become a teacher after reading Jonathan Kozol’s “Savage Inequalities” while a student at George Washington University. She wanted to help make sure that all kids, including those living in the nation’s poorest communities, got the kind of education she received.

“I was brought up learning that education is the silver bullet to solve any problem,” she said. “I wanted to be a part of the solution.”

She spent two years as a Teach for America corps member in Gary, Ind., before returning to the District in 2010. She chose to work at D.C. Prep because of its efforts to weave academics with character development.

“As teachers and as schools, we have the opportunity to teach students really strong habits that will help them long-term,” King said.

She was also drawn to the DC Prep, she said, because of its emphasis on collaboration among teachers.

“Teaching is a constant process of learning and adjusting,” she said. “There are so many amazing things happening in education, and we can really learn from each other.”

Rick Cruz, who recently took the helm of D.C. Prep from founder and outgoing chief executive Emily Lawson, said King has kindred spirits in her colleagues — teachers and administrators who not only collaborate but also are never quite satisfied with their work. It’s a culture that defines D.C. Prep and has helped make it successful, Cruz said.

The Edgewood middle school is the highest-ranked charter school in the city.

“There’s no secret sauce, it’s just that kind of hard work of reflection and attention to improving,” Cruz said. “Everyone’s hard on themselves.”