The city and the unions representing teachers and principals reached a deal Monday to make up for the week lost to the storm Sandy by taking three days from the mid-winter break in February and replacing a half day in June with a full day.

Classes will now be in the session Wednesday, Feb. 20 through Friday, Feb. 22 and the June 4 clerical half day will become a full day of class instruction.

A joint statement by Chancellor Dennis Walcott, Ernest Logan, president of the Council of School Supervisors and Administrators, and Michael Mulgrew, president of the United Federation of Teachers said:

“We are pleased that the City, the CSA and the UFT reached an agreement on making up school days lost as a result of Hurricane Sandy. Teachers, principals, and the school community made an extraordinary effort to get our schools back online after the storm, and by working together, we were able to open most schools with minimal disruption. It is just as important that we recover the time lost, and this agreement will provide students with additional class instruction.”

In his letter to union members, Mulgrew tried to reassure teachers that their vacation plans would not be too disrupted and also explained that it is state law to provide a minimum of 180 days of instruction every school year, meaning something had to give in the school calendar after students unexpectedly lost a week of learning time because of the storm.

He told teachers that they would not be punished for taking time off during the mid-winter week if they already had plans to do so. Specifically, any absences during the latter half of that week won’t be used against teachers in disciplinary hearings or end-of-year rating.

“We realize that a number of you have already bought airline tickets or cruises for the midwinter break and risk losing a lot of money if you canceled those trips now,” he wrote. “At our insistence, the DOE agreed to allow any UFT member who has purchased a vacation before Nov. 19 to go on the purchased vacation and instead deduct those days from his or her CAR bank. If they have no days in their leave bank, they can either borrow days or take the days as days without pay.”

He also said other school districts in New York have taken similar steps.

“Eleven school districts on Long Island have already agreed to make up the time by taking away all or part of the February break and/or the spring break” Mulgrew wrote.

Earlier on Monday, the chancellor was joined by Mayor Michael Bloomberg and other elected officials as they marked the opening of 12 more schools that were severely damaged by the storm wrought by Hurricane Sandy. According to the Department of Education, more than 5,400 students, teachers and staff returned to work in their own buildings on Monday.

“We know that at a time of disruption and dislocation for so many New Yorkers, our public schools can be a much-needed anchor for families,” said Mayor Bloomberg. “That’s why we’ve been working so hard to get our schools open again. We still have more work to do, and thanks to the extraordinary efforts of our school engineers, custodians and facilities staff, we will continue to return our students to their classrooms as quickly as possible.”

They spoke at P.S. 43 in Far Rockaway which suffered substantial flooding, loss of power and heat and other storm damage. Facilities staff pumped about five feet of water out of the basement and two feet on the first floor of the building. They also cleaned the site, installed a generator and temporary boilers and repaired the roof.

To date, 7,800 students from 18 schools remain at their reassigned sites due to ongoing repair work.

“Our most important task was getting students back in the classroom as soon as possible,” said Walcott. “We will continue to make repairs as quickly as possible in order to get the remaining 18 schools reopened.”