New Yorkers following Chicago’s snowballing union-district standoff over plans to extend the school day may not realize that similar conversations take place inside city schools every year.

Chicago’s new mayor, Rahm Emanuel, and his schools chief, former New York City deputy Jean-Claude Brizard, are pushing schools to add 90 minutes to their 5-hour-long days, among the shortest in the nation. But they have offered teachers only 2 percent more pay, raising the ire of the teachers union, whose president, Karen Lewis, has said Emanuel is creating “a nightmare” by asking union members to override their union contract.

Even though the union has filed a lawsuit over the plan, Emanuel and Brizard decided to shop the proposal school by school, and teachers at at least nine schools have voted to extend their working hours—and the instructional day. The city and the teachers union send out warring press releases each time another school takes a vote.

Staff at New York City schools routinely take similar votes, but with less fanfare. There has been no system-wide push for a longer school day in years, and educators do not foresee a Chicago-style showdown repeating in New York.

That’s in part because the average New York City school day is already much longer than Chicago’s, and slightly longer than other major cities’, with many students in school for 6.5 hours or more. In addition, the district already struck a flexible deal with the union five years ago to extend the school day by 37.5 minutes four days a week for at least 290,000 city students, mostly those who struggle academically. How that time is spent is, to a large degree, up to each school.

Researchers say it is almost impossible to make a good estimate of the length of the New York City school day—something that one Chicago columnist found last week when he tried to tally the numbers—because instructional time requirements vary by grade-level and subject, and principals and teachers can decide together how they want to structure parts of the school day. 

Researchers tracking the length of the school day in major cities for National Center on Time and Learning were not able to do so for New York City because the system is decentralized and the facts vary greatly from school to school, according to a Blair Brown, a spokeswoman.

The system’s decentralization means that city schools have a high degree of individual decision-making power over how to divide that time and whether or not to add more, either by bringing after-school programming to the school via independent community organizations or getting creative with teachers’ schedules.

The local decisions are made possible by a clause in the teachers contract that allows a “school-based option” on scheduling and other matters: Schools can lengthen or rearrange their days if 55 percent of their staff vote yes.

In 2006, school-based decision-making about time got a boost when the city and teachers union agreed on a plan to extend the day by 37.5 minutes — for teachers and small groups of struggling students. The new time was rolled out differently at different schools, with many adding a period to the end of the day but some integrating it into the day or making the extra time mandatory for all students. Other schools started to let teachers use the time to plan lessons after former chancellor Joel Klein told them they could.

“There are creative models that schools even within the union agreement are expanding time and seeing union results and doing it within the budget,” said Jennifer Davis, president of the National Center on Time and Learning, which advocates for longer school days. “Why aren’t more schools doing that? Because there has to be a leadership commitment to really putting that issue on the table.”

Brown cited Brooklyn’s Generation School in Canarsie as one district high school that keeps its students in class longer by deviating from the norm. It has added extra minutes to its school day and 20 extra days to its school year by staggering teachers’ schedules and vacation periods to have them working no more than 180 days.

At the Washington Heights Expeditionary Learning School, for the past six years teachers have voted for school periods to last 65 minutes—about 20 minutes longer than the typical city class period, according to Brett Kimmel, the school’s principal. But to keep the school day running on schedule, he has eliminated passing periods—the time between class periods that students usually use to traverse the halls or pick up more school supplies.

“Some schools will say class ends at 9:05 and the next class begins at 9:10. We don’t do that,” he said. “Our kids are organized so that they get up and go right across the hall to the next classroom, and that class begins very efficiently.”

In many cases, schools will lengthen the day beyond five periods by hiring outside organizations to teach extra-curricular classes such as drama, music and sports.

That’s where nonprofit groups like the After School Corporation fit into the picture.

“The new chancellor hasn’t made that policy that every school should have a longer school day, but I do think there is a general support and momentum growing for it,” sad Lucy Friedman, president of The After-School Corporation, which operates programs in 16 city schools.

She said the cost of after-school programming is still a main barrier for some schools, even though New York has the largest municipal funding for extended day programming.

To cut costs, Friedman said TASC tries to promote collaboration between after school programming providers and the educators who work in those schools during the academic school day. At Thurgood Marshall lower school, for example, students can chose to stay in class until 5:15 or later after their last academic period ends by taking organized drama, dance, creative writing and sports classes as well as a homework-tutoring class—subjects that some schools would chose to hire full-time teachers for if they had the funds.

“There’s a growing recognition that six hours a day isn’t going to prepare kids for life, for being career and college ready,” Friedman said.