Antwan Wilson greets students at the Brightwood Education Campus as he begins his first official day as chancellor of D.C. Public Schools. (Sarah L. Voisin/The Washington Post)

It was the middle of the academic year, but Wednesday marked the first day of school in the District of Columbia for Antwan Wilson.

The new D.C. schools chancellor spent the morning high-fiving students as they entered school. He watched elementary students solve problems with fractions, and then he sat with high school students for a lunch of pulled chicken with rice and a pineapple parfait.

“It’s an awesome day because it’s a great day for me to get out to see what is happening in our schools, meet with a lot of teachers, support our principals, talk to students and learn a lot about the work that has been happening in DCPS,” Wilson said.

He will have to catch up quickly. After years of steady improvement in the school system, Mayor Muriel E. Bowser (D) chose Wilson, 44, to address some of its deep and persistent problems, especially achievement gaps.

The former superintendent of the Oakland Unified School District in California is the first outsider to take the helm of D.C. Public Schools since Michelle Rhee in 2007. He will inherit a school system that has changed much in that decade, under the tenure of Rhee and then Kaya Henderson, who served as chancellor from 2010 to last year. More of the system’s students are now mastering math and reading concepts on standardized exams. And after years of declining enrollment, more families are choosing the 48,000-student school system.

But deep divisions remain in the schools. Students of color lag far behind their white peers on almost every measure, including graduation rates and test scores. On the 2016 PARCC exam, a national test linked to the Common Core academic standards, 72 percent of white students reached or exceeded proficiency in math, compared with 13 percent of black students.

The school system still loses students as they transition to middle grades, and it continues to compete for students and resources with public charter schools.

“We have more momentum than most places in the country, but unfortunately that doesn’t mean that we have closed the achievement gap,” said Deputy Mayor for Education Jennifer Niles. “Very clearly, that’s the most important thing that we have asked the chancellor to do.”

Wilson’s first stop of the day was at Brightwood Education Campus, a school in Northwest for students in prekindergarten through eighth grade. Its enrollment rose from 573 students in 2012-2013 to more than 700 in the past school year. But the majority of its students are not meeting math and reading standards on national tests.

Wilson and Principal Maurice Kennard stood outside the school as students made their way to class. Many parents and students were hesitant to walk in, staring at the television cameras that flanked Wilson.

“It’s okay, you can come in,” he said, flashing a smile and waving to a group of students.

Between the good mornings and hellos, Wilson asked Kennard more about the school. Does it teach physical education? How is the school divided, since it has elementary and middle grades? Do children eat breakfast at the school?

Kaylin Barber, 7, a first-grader, slowly made her way to the front door, staring at the ground, most of her face wrapped in a beige scarf. Kennard noticed something was wrong.

“You okay?” Kennard asked.

She was worried her teacher would be mad because she left her backpack at home. Her homework was in it. Kennard promised to call the teacher before Kaylin got to class.

“You noticed she cares about it,” Wilson told Kennard.

These are the sorts of things Wilson said he looks for in schools. He wants to see students who care about academics. He wants them engaged in class, talking to classmates and teachers. He wants them to like school because education experts say students who do so perform better academically.

But he is also looking for ways that teachers are challenging students and encouraging them to collaborate. Wilson said he was pleased to see that in many classrooms, students were not sitting in straight rows but were instead seated in groups or circles to facilitate teamwork.

In a fifth-grade math classroom, he bent down to talk to 11-year-old Jose Ventura, who was looking at homework with a group of students.

What were they reviewing? Wilson asked in a whisper.

Improper fractions.

Wilson asked Jose what he does when he gets stuck. “I ask my teacher,” he said. But what if the teacher is not around? Jose said he turns to classmates for help.

“That’s what I want to hear,” Wilson later said in an interview. “And then I saw them building upon each other’s conversations and ideas and respectfully disagreeing. We have to teach that. I want to see that in action.”

The next few months will look a lot like this first day for Wilson, who spent Wednesday at campuses including Alice Deal Middle School. Wilson, Bowser and Niles surprised science teacher Jan Schuettpelz with news that she is the DCPS teacher of the year.

Wilson has already visited 18 schools, counting others he previously saw. He plans to go to each of the system’s 115 schools this year. He has not yet announced initiatives to close the achievement gaps.

“We will have the opportunity to visit with many teachers, parents, students and leaders to talk about the great things that are happening but also hear from them on how we can make it even better,” Wilson said.