size matters

NYC class size limits could boost learning — but in practice, they often don’t. A new study explains why.

PHOTO: Erin Einhorn
Rynell Sturkey, a first-grade teacher at Paul Robeson Malcolm X Academy on Detroit's west side often manages jam-packed classrooms of 37 kids or more. Her students have no music or art or gym. “They’re with me all day in this room. We’re tired,” she said.

A contentious debate about how much class size actually matters is getting some new data — and ammunition for both sides.

While former Mayor Michael Bloomberg dreamed of firing half the city’s teachers and paying the remaining superstars twice as much to teach larger classes, Mayor Bill de Blasio has argued that small classes are essential. But as classrooms have become more crowded, how much pressure should there be to reverse that trend?

A new study focusing on New York City offers some evidence for both poles of the debate: Reducing class sizes can significantly increase student learning, but those gains are often canceled out in the short run by the lower-quality teachers who wind up staffing them — and by disruptions linked to their quick hiring.

“My paper is quite supportive of the argument that class size [reduction] boosts student achievement,” explains Michael Gilraine, the study’s author, who will start this fall as a professor at New York University. But “when you reduce class sizes you’re going to have a trade-off because you need to bring in new teachers — and that might have its own independent effect.”

Gilraine’s findings come at an opportune moment for organizations like Class Size Matters and the Alliance for Quality Education, which recently filed a complaint with the State Education Department claiming the city has failed to meet required class size reduction targets.

Using data from 473 city schools, Gilraine isolated the effect of class size reductions by looking at third- through sixth-grade classes that moved just above or below the 32-student cap required for elementary grades. Classes that moved from 32 to 33 students, for instance, would have to reduce class sizes by adding a new teacher, while classes that moved from 33 to 32 students could reduce class sizes without adding a new teacher — isolating the effect of the newly added teacher.

Looking at schools near the cap between 2009 and 2014, Gilraine found that reducing class size by an average of four students produced gains in reading and math scores equivalent to roughly two and a half months of extra learning.

But there’s a big catch: The classes that shrank by bringing in a new teacher saw essentially no boost in student achievement. And since roughly 50 percent of the classes Gilraine examined depended on newly hired teachers, the overall effect of the class size reductions was cut in half.

Though Gilraine did not rigorously assess why half of these class size reductions didn’t boost student learning, he said there are a couple of likely reasons. For one, newly hired teachers may be less experienced or lower quality.

Second, there could be disruptions associated with bringing in new employees. Since class sizes were frequently lowered after the teachers union filed grievances, some reductions happened after the school year had already started — potentially disrupting classes mid-year.

The study has not been published or peer-reviewed, but Thomas Dee, director of Stanford’s Center for Education Policy Analysis, said it appeared to be rigorous. He said the findings are not entirely surprising but illustrate the importance of understanding how class size policies play out across systems, not just in the context of smaller experiments.

Dee pointed to the gold standard of class size research: a landmark randomized experiment in Tennessee conducted in the 1980s that found significantly reducing class sizes in early grades improved student learning. “That really established in people’s minds that small class sizes — though they’re expensive — are effective,” he said. But “the kinds of things that might work in a small-scale study may not scale well.”

Gilraine’s findings dovetail with research on California’s billion-dollar effort to systemically lower class sizes in the 1990s, which showed reducing class sizes led to gains in reading and math but was dampened by hiring less experienced teachers.

Dee added that one conclusion to draw from Gilraine’s study is that class size reductions may be more effective when they’re targeted — at high-need schools, for example — rather than enforced system-wide.

Leonie Haimson, executive director of Class Size Matters, said the study shows the city must do more to reduce class sizes — and do so more proactively. She emphasized that the city could avoid disruptive hiring practices, and that there’s no reason to assume hiring more teachers would reduce the overall quality of teaching in the long run.

“In a well-crafted class size reduction, you’re going to hire teachers earlier on and those teachers are going to be higher quality and stay longer and become more effective” she said. “If anything, this paper is an indictment of the current system.”

The New Chancellor

Tell us: What should the new chancellor, Richard Carranza, know about New York City schools?

PHOTO: Christina Veiga
A student at P.S. 69 Journey Prep in the Bronx paints a picture. The school uses a Reggio Emilia approach and is in the city's Showcase Schools program.

In a few short weeks, Richard Carranza will take over the nation’s largest school system as chancellor of New York City’s public schools.

Carranza, who has never before worked east of the Mississippi, will have to get up to speed quickly on a new city with unfamiliar challenges. The best people to guide him in this endeavor: New Yorkers who understand the city in its complexity.

So we want to hear from you: What does Carranza need to know about the city, its schools, and you to help him as he gets started April 2. Please fill out the survey below; we’ll collect your responses and share them with our readers and Carranza himself.

The deadline is March 23.

buses or bust?

Mayor Duggan says bus plan encourages cooperation. Detroit school board committee wants more details.

PHOTO: Denver Post file
Fourth-graders Kintan Surghani, left, and Rachel Anderson laugh out the school bus window at Mitchell Elementary School in Golden.

Detroit’s school superintendent is asking for more information about the mayor’s initiative to create a joint bus route for charter and district students after realizing the costs could be higher than the district anticipated.

District Superintendent Nikolai Vitti told a school board subcommittee Friday that he thought the original cost to the district was estimated to be around $25,000 total. Instead, he said it could cost the district roughly between $75,000 and a maximum of $125,000 for their five schools on the loop.

“I think there was a misunderstanding….” Vitti said. “I think this needs a deeper review…The understanding was that it would be $25,000 for all schools. Now, there are ongoing conversations about it being $15,000 to $25,000 for each individual school.”

The bus loop connecting charter and district schools was announced earlier this month by Mayor Mike Duggan as a way to draw kids back from the suburbs.

Duggan’s bus loop proposal is based on one that operates in Denver that would travel a circuit in certain neighborhoods, picking up students on designated street corners and dropping them off at both district and charter schools.

The bus routes — which Duggan said would be funded by philanthropy, the schools and the city — could even service afterschool programs that the schools on the bus route could work together to create.

In concept, the finance committee was not opposed to the idea. But despite two-thirds of the cost being covered and splitting the remaining third with charters, they were worried enough about the increased costs that they voted not to recommend approval of the agreement to the full board.  

Vitti said when he saw the draft plan, the higher price made him question whether the loop would be worth it.

“If it was $25,000, it would be an easier decision,” he said.

To better understand the costs and benefits and to ultimately decide, Vitti said he needs more data, which will take a few weeks. 

Alexis Wiley, Duggan’s chief of staff, said the district’s hesitation was a sign they were performing their due diligence before agreeing to the plan.

“I’m not at all deterred by this,” Wiley said. She said the district, charters, and city officials have met twice, and are “working in the same direction, so that we eliminate as many barriers as we can.”

Duggan told a crowd earlier this month at the State of the City address that the bus loop was an effort to grab the city’s children – some 32,500 – back from suburban schools.

Transportation is often cited as one of the reasons children leave the city’s schools and go to other districts, and charter leaders have said they support the bus loop because they believe it will make it easier for students to attend their schools.

But some board members had doubts that the bus loop would be enough to bring those kids back, and were concerned about giving charters an advantage in their competition against the district to increase enrollment.

“I don’t know if transportation would be why these parents send their kids outside of the district,” Angelique Peterson-Mayberry said. “If we could find out some of the reasons why, it would add to the validity” of implementing the bus loop.

Board member LaMar Lemmons echoed other members’ concerns on the impact of the transportation plan, and said many parents left the district because of the poor quality of schools under emergency management, not transportation.

“All those years in emergency management, that drove parents to seek alternatives, as well as charters,” he said. “I’m hesitant to form an unholy alliance with the charters for something like this.”