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When Gov. Kathy Hochul signed a new law last year that would slash class sizes in New York City, praise came in from many quarters.

Teachers, along with their union, hailed the move as a victory that would improve classroom conditions and boost learning. Education activists said smaller class sizes would benefit the most vulnerable students. Lawmakers in Albany, who overwhelmingly passed the bill, rejoiced. 

There are good reasons for this enthusiasm. Studies have found that students often learn more in smaller classes. Some research suggests that children from low-income families, who constitute a majority of New York City students, benefit the most. Plus, smaller classes are popular with parents and teachers alike.

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But in recent months, some of the new law’s costs and tradeoffs have come into sharper focus. A Chalkbeat analysis shows that because the city’s highest-poverty schools already have smaller classes, they stand to benefit the least from the state’s class size cap. This aligns with recent reports from the New York City Department of Education, the city’s Independent Budget Office, and The Urban Institute.

Researchers who have studied class size say that these findings raise troubling equity concerns. The class size cap could mean that new resources will be funneled not to the schools that have the greatest needs or lowest test scores but to some of the city’s better-off schools. 

The cap could exacerbate teacher shortages in high-poverty communities by creating a hiring spree that encourages more advantaged schools to poach teachers. And city officials, including Mayor Eric Adams, said they’ll be hard pressed to afford the class size mandate absent additional state money.

“Some of the less advantaged schools already have smaller class sizes — in that way, it’s not putting the additional money you have into the schools that probably need it the most,” said Susanna Loeb, a Stanford University researcher who has studied New York City schools.

Highest-needs schools already have smallest class sizes

The new cap dramatically reduces the number of students allowed in a single classroom. 

Under the previous rules, classes were generally capped at 30 to 34 students, depending on the grade, with 25 students in kindergarten. Under the new law, classes may not exceed 20 students in kindergarten through third grade, 23 students for grades 4-8, and 25 students in high school. Physical education and classes involving “performing groups” are limited to 40 children.

But the reductions in class size will not be shared evenly once the law is fully implemented over five years.

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At the city’s highest poverty schools, only 38% of classrooms are larger than the new caps allow, according to a Chalkbeat analysis of city data from last school year. By contrast, at low- to mid-poverty schools, 69% of classrooms are above the caps.

To bring schools into compliance with the law, which will take full effect in 2028, the city will need thousands of new teachers at an annual cost of $1.3 billion to $1.9 billion, according to projections from the Education Department and the city’s Independent Budget Office. That’s at least 4% of the department’s operating budget

At overcrowded schools that need more classroom space to reduce class sizes, the School Construction Authority estimated the costs could run tens of billions of dollars.

But since the state has not earmarked new funding attached to the class size law, it remains unclear how the city will pay for it. Experts warn of difficult tradeoffs. Additional dollars spent reducing class sizes on lower-need campuses could instead be directed to the city’s highest-need schools — to, say, hire more tutors to combat pandemic learning loss or additional social workers to address student mental health challenges.

In Brooklyn’s District 16, which includes much of Bedford-Stuyvesant and where the vast majority of students come from low-income families, 36% of classrooms were above the new class size caps. That’s the second-lowest rate of the city’s 32 districts. 

NeQuan McLean, the president of District 16’s local parent council, said he wasn’t aware that higher-need districts are less likely to benefit from the new law, noting there wasn’t much public debate of that issue when the law passed.

“I would definitely have a problem with resources being pulled from low-income districts to go to high-income districts when investments need to be made in underserved districts,” McLean said. “We can’t use the method of robbing Peter to pay Paul.”

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He said additional investments in his district are sorely needed, from upgraded gyms and bathrooms, to additional wraparound services in schools to combat food insecurity. He also wants more on-campus health services and dental clinics, as students often miss school to go to those appointments.

There will be tradeoffs at lower-need schools, too, as school leaders may be required to direct more resources to staff smaller classes, potentially forcing cuts to other programs. City officials may also have to cap enrollment at some schools. 

“Maybe principals have decided they want slightly larger class sizes [in exchange] for a math coach,” said Matthew Chingos, an Urban Institute researcher who recently published a report about the impact of the class size caps and serves on a city advisory group on the issue. “It may force some tradeoffs that people didn’t fully appreciate.” 

Supporters point to advantages of small classes

The law’s backers contend that small classes are a basic necessity with broad benefits to students. 

Jake Jacobs, a Bronx art teacher, said it is difficult to offer individual support when his classes exceed 30 students. “Those classes were nightmares because of it,” he said. Despite some of the tradeoffs of the law, “as a teacher I think the advantages outweigh the disadvantages.”

As for concerns about equity, supporters point out that most students in New York City are from low-income families, so much of the class size cuts will still redound to their benefit.

“The law actually lowers class sizes for a higher number of high-need kids compared to lower-need kids,” said Christina Collins, the director of education policy at the United Federation of Teachers, which pushed for the new caps. 

Collins and other supporters emphasize that the law also requires the Education Department to prioritize higher-need campuses first as the new caps phase in. (However, experts note this doesn’t address the key equity issue, since all schools regardless of poverty level will be required to meet the new class size limits within five years.)

Asked about concerns that the law would still require the city to funnel resources to schools with fewer high-need students, Collins pointed to education programs that give students access to the same resources regardless of family income, such prekindergarten or free meals

Proponents also contend that there is funding available to cut class sizes, pointing to recent boosts in state education dollars that stem from a decades-old lawsuit that argued New York’s schools were not properly funded. 

“The courts mandated that every kid get a sound, basic education. And their mandate cannot be achieved when kids are still in excessively large class sizes,” said state Sen. John Liu, who sponsored the class size legislation. 

The city’s Education Department may use increases in state funding to reduce class sizes. But officials note the department has already committed the money to other priorities, including for the first time fully funding the city’s own school budget formula, which channels more resources to schools that enroll higher-need children.

Mayor Adams has warned that complying with the class size mandate will restrict city officials from spending education dollars as they see fit. 

“Clearly we should use taxpayers’ dollars to focus on equity — not equality, equity,” Adams said at a press conference last September. “There are certain school districts that need more,” he added. “We’re taking away the chancellor’s ability to focus on where the problem is, and the governor made the decision to sign it.”

A spokesperson for Gov. Hochul did not respond to questions about the equity implications of the law.

Unintended consequences loom large

Hiring thousands of new teachers in New York City could prove a particular challenge, especially at a moment of rising teacher turnover. A hiring spree might force schools to bring on less skilled or less qualified educators, which could limit the gains from smaller classes. 

In one study of New York City, Michael Gilraine, an economist at New York University, found that when schools reduced class size without having to hire a new teacher, there were large improvements in student test scores. But when they had to add a teacher to get class sizes down, the benefits from smaller classes were swamped by a decline in teacher quality.

“The results indicate that smaller class sizes do improve student achievement,” wrote Gilraine. “Policy makers and school administrators need to be mindful, however, that these gains can be offset by changes in teacher quality.” 

Research in California has highlighted a similar tradeoff, though it suggests that the problem dissipates over the longer term.

Higher-need schools typically bear the brunt of teacher shortages. For instance, an older study in New York City found that better teachers were more likely to migrate from lower-performing schools to high-performing ones, a concern echoed in the city’s working group on class size reduction.

One leader of a Manhattan middle school, where most classes already met the new class size caps last school year, said he’s concerned that higher-performing schools in the district may poach quality educators.

“How many teachers from the lower-performing schools are going to go [to higher-performing schools] because they can get paid the same amount and have an easier life?” said the principal, who spoke on condition of anonymity to speak frankly about the class size cap’s impact on their campus. “That’s my bigger worry honestly.” 

New York City does not offer additional pay to teachers working in higher-needs schools to potentially counteract this effect.

“It’s hard to recruit teachers right now” and high-poverty schools typically have a harder time doing so, said Loeb, the Stanford professor. “Adding class size reduction may in fact escalate that.”

Collins, of the UFT, says there should be efforts to expand the pipeline of new teachers to meet rising demand.

For now, officials don’t have clear answers to these challenges and much remains uncertain about how the city will implement the new law. The Education Department has convened a task force that includes advocates and policy experts to gather input.

The law also includes a handful of exemptions to the class size mandate, including for schools that are overenrolled, would face significant economic hardship to comply, or or have insufficient teachers in subjects that are difficult to staff. The Education Department and the unions representing teachers and school administrators must all agree to those waivers. If they don’t, the decision falls to an arbitrator.

“It’s not clear how those decisions are going to be made — and school communities that wind up losing valuable dollars are going to be up in arms,” said Aaron Pallas, a professor at Columbia University’s Teachers College who has studied New York City schools.“I would like that process to be as open and transparent as possible.”

Regardless of the challenges, Liu, the state senator who championed the law, remains sanguine. “I don’t think anybody will say 10 years from now that, ‘Oh, this was the wrong thing to do,’” he said.

Alex Zimmerman is a reporter for Chalkbeat New York, covering NYC public schools. Contact Alex at azimmerman@chalkbeat.org.

Matt Barnum is interim national editor, overseeing and contributing to Chalkbeat’s coverage of national education issues. Contact him at mbarnum@chalkbeat.org.