More than 100 teachers and other staff members at two D.C. schools learned this week that they must reapply for their jobs after Chancellor Kaya Henderson decided to “reconstitute” the schools in an effort to spur improvement.

Cardozo High and Patterson Elementary schools have struggled for years with low test scores, and in such cases, Henderson has the power to reconstitute — remove an entire staff and then rebuild it.

“When a school continues to underperform, DCPS has to take serious action to make improvements,” Henderson said in a statement. “DCPS has determined that these schools are in need of a fresh start in order to provide the rigorous academics we require of all our schools.”

Teachers said the news, which school system officials delivered Monday afternoon, blindsided them.

“It’s very demoralizing,” said Candi Peterson, a Cardozo social worker who wrote about teachers’ reactions on her blog. “People are really just blown away.”

Under the federal No Child Left Behind law, reconstitution has become one tool officials can use to turn around chronically low-performing schools. The District has reconstituted more than two dozen schools since 2008, and the results are mixed: Some schools have improved, while others have continued to struggle.

Cardozo, in Northwest, was reconstituted in 2008, and its test scores have improved only marginally. About one-quarter of students are proficient in reading and one-third in math, while 42 percent graduate within four years.

Teachers say that trying to improve those results by replacing staff is a simplistic approach that ignores profound challenges. Many students arrive at Cardozo far behind grade level. One-third are special-education students; one-quarter have limited proficiency in English.

“It’s really disheartening,” said veteran Cardozo English teacher Frazier O’Leary, who has lived through two reconstitutions of the school. “To be labeled as failures time and time again is an affront to our professionalism.”

Even though other city schools have lower test scores, Henderson said, circumstances call for reconstitution at Cardozo and Patterson.

Cardozo is facing a transition next year as it moves into a newly modernized building at 13th and Clifton streets NW in Columbia Heights, Henderson said. The high school is also morphing into a secondary campus with the addition of sixth- to eighth-grade students from Shaw Middle School at Garnet-Patterson, which is closing in June.

“In consultation with school leadership, we decided reconstitution would be the best move to ensure the success of the new school,” Henderson said.

Cardozo Principal Tanya Roane, who will decide which staff members to rehire, did not respond to a request for comment.

At Patterson, east of the Anacostia River in Ward 8, test scores have declined over the past several years. Fewer than one-third of students are proficient in math; 28 percent are proficient in reading. After years of leadership churn, the school now has a stable principal in Victorie Thomas, Henderson said. Thomas did not respond to a request for comment.

“Reconstituting the school allows for the principal to hire the staff she and DCPS believe will put Patterson on a pathway toward success,” Henderson said.

Teachers at both schools said they’ll have 15 minutes each to interview with their principals over the next three days and hope to know by next Wednesday whether they’ll keep their jobs.

Staff members who don’t interview or aren’t rehired will be “excessed,” which means they will have 60 days to find another position within the school system.

Those who don’t find a job within that period and who are rated effective or above on annual IMPACT evaluations can choose to take a $25,000 buyout or a grace year of employment to continue looking for permanent positions.

Those rated below effective on their annual IMPACT evaluation will be fired.

Cardozo and Patterson teachers said they were upset by the timing of the announcement: With only a few weeks left before summer break, they said, many vacancies in DCPS and neighboring school systems have already been filled, limiting options for teachers who are not rehired.

School system spokeswoman Melissa Salmanowitz said displaced teachers are encouraged to participate in three upcoming hiring fairs. “This is the time when principals have a much better sense of their needs,” she said.