Mayor Muriel E. Bowser listens to questions from a class of third-graders. (Jabin Botsford/The Washington Post)

Say goodbye to long summer breaks, at least in a wide swath of Southeast Washington. Starting next fall, nearly 4,000 students in some of the city’s poorest neighborhoods will attend school year-round.

Ten D.C. public schools will move to extended-year schedules next fall, city officials said Wednesday, the latest push by the District to embrace a learning calendar used at more than half of the city’s charter schools.

An extended year means that students will have 20 more school days per year than their peers at other D.C. public schools. But those days will also be organized differently: Instead of a long summer break, students will have shorter and more frequent breaks over a school year that runs 200 days through all 12 months.

The idea is to eliminate “summer learning loss” among the city’s most underserved communities, officials said.

D.C. Public Schools Chancellor Kaya Henderson (Jabin Botsford/The Washington Post)

“We will offer students the equivalent of an extra year of learning by the time they reach the eighth grade,” D.C. Mayor Muriel E. Bowser (D) said Wednesday.

The schools are all elementary and middle schools. Most feed into one another and are east of the Anacostia River in some of the District’s poorest neighborhoods, where the achievement gap is often the widest compared with more-affluent neighborhoods and where fewer parents can pay for summer camps and seminars.

“These are schools where not all the kids are reaching their potential,” said Jennifer C. Niles, deputy mayor for education.

The extended school year will allow for more academic instruction time as well as for electives — or “specials,” as they’re called in elementary schools — including performing arts, languages and physical education, Niles said.

Seasonal breaks will include additional “intersession” programming, when students will be able to “dive deeper” into special projects or reading development, she said.

More than half of D.C. charter schools already run on extended schedules, but only one public school does, Niles said. The shift is pending a budget appropriation by the D.C. Council.

The change immediately drew concern from the Washington Teachers’ Union.

Union President Elizabeth Davis said labor leaders have seen little data from city officials showing that extended scheduling really works.

“In the lowest-performing schools, the focus has been on tests — reading and math — not providing students a well-rounded curriculum,” she said. “Simply extending the time is not the answer.”

Davis said that Bowser and Schools Chancellor Kaya Henderson made their decision without consulting any of the four unions that represent school workers in the District. She said that the WTU has submitted a complaint about the process.

Teachers at some of the schools, she said, are “being told that ‘if you’re not interested in working in a school with an extended school day or year, then you’d have to find another job.’ ”

Democrats for Education Reform, an advocacy group that has backed charter schools, released a statement Wednesday in favor of the move.

“Education isn’t one-size-fits-all, and our current 180-day school year and 6 1 /2-hour school day is not enough for all students, particularly in our highest-need schools,” said the group’s director, Catharine Bellinger.

The schools affected by the schedule change are H.D. Cooke Elementary in Adams Morgan and, in Wards 7 and 8, Garfield, Hendley, King, Randle Highlands, Thomas and Turner elementary schools and Hart, Johnson and Kelly-Miller middle schools.