The head of the Newark Teachers Union is calling on the district to abolish school-improvement efforts that ask teachers at certain schools to work longer hours in return for extra pay.

About 30 district schools have extended days, which teachers must agree to in writing each year. According to an email that the union president sent to the district’s interim superintendent on Tuesday, some principals pressured teachers to sign those agreements this week before they have had a chance to look for positions at other schools.

But the union chief, John Abeigon, has decided to use that grievance to renew past calls to dismantle all of the district’s extended-time programs entirely. In his email to Interim Superintendent Robert Gregory, Abeigon called the programs “the last vestiges of a failed reform model” enacted by Cami Anderson, a former state-appointed superintendent with whom the union clashed bitterly.

Now that Newark’s elected school board has regained control of the schools, Abeigon said the district should restore an after-school initiative favored by the union and scrap the extended-day model.

“It’s a failure,” Abeigon said in an interview. “Now we’re trying to take advantage of the return to local control to get rid of it.”

The extended time was built into a 2012 contract negotiated by Anderson and the teachers union, which was hailed nationally as a model of district-labor cooperation. Under the contract, the superintendent could designate a limited number of so-called “Turnaround” schools whose academic performance needed to improve. In exchange for a $3,000 bonus, teachers who signed an annual agreement would work up to an hour longer each day and attend training sessions in the summer and on some weekends. The schools also were freed from some contract rules around scheduling, making them similar to charter schools that generally are not restricted by teachers contracts.

Some schools were insulted by the Turnaround label, sparking student protests. In some cases, teachers who refused to sign the agreements were transferred to other Turnaround schools, where they reportedly operated on different schedules than teachers who had signed on.

Still, about two-thirds of surveyed teachers said the extra time with students was valuable, according to a 2016 study commissioned by the district that looked at schools — including Turnaround schools and those in another school-improvement program, called “Renew” — where teachers agreed to extended schedules. Last year, the union and district negotiated a new teachers contract that goes to 2019 and includes both the Turnaround and Renew programs.

In response to Abeigon’s call Tuesday to do away with extended schedules, district officials pointed to last year’s agreement.

“The district signed a contract in 2017 with the Newark Teachers Union that included the opportunity for schools to provide extended learning time, because we believe that more learning time can help improve learning outcomes for students,” said Larisa Shambaugh, the district’s chief talent officer, in a statement. “We look forward to working with the NTU to continue to ensure that this portion of the contract is implemented in a way that allows for all of our students and educators to be successful.”

The union has long raised doubts about whether the extra time is actually improving school performance. But the latest outcry appeared to be prompted less by fundamental concerns about the model than about how it is being carried out.

According to the union, some school administrators have revised the “election to work agreements” that outline teachers’ responsibilities at extended-time schools without consulting the union. Teachers would likely welcome some of the revisions — such as fewer trainings during the summer or on Saturdays — but union officials said they must still sign off on any changes.

In addition, some principals ordered teachers to sign next school year’s agreements this week. The union said that is unfair because the district has not yet hosted its annual job fair, meaning teachers are being asked to commit to stay at their current schools without being able to explore other options first.

As evidence, the union supplied an email from the principal of McKinley Elementary School to her staff saying that teachers who did not sign the agreements by Friday “will be removed from the McKinley Roster” and that teachers who do sign “obviously can’t change your mind to transfer later on.”

Another email provided by the union showed that the staff at Luis Muñoz Marin School for Social Justice had been told to sign their agreements by this Monday. However, they were informed Tuesday that the agreement had been modified and were told to sign the revised agreements by the end of that day.

Marin is part of the Renew program, while McKinley is a Turnaround school. Neither principal responded to emails seeking comment.

In his message to Interim Superintendent Gregory — which was titled “Turnaround Schools Dead: End the EWA threats now!” — Abeigon said that multiple principals had sent similarly “coercive” emails to teachers in recent weeks. He said the changes to the agreements violated the teachers contract. And he called on Gregory to “discuss replacing” the extended-time model with an after-school program that would only target students who need extra support.

“Dozens of your dedicated employees are crying out for help and your leadership,” Abeigon wrote, “as their backs are up against a wall you have the power to take down.”