Each year, nearly a quarter of all New York City teachers move within their schools to a new grade level assignment or a new subject. And those reassignments can depress their students’ achievement, probably as a result of teachers adapting to their new position, concludes a new study.
Teacher “churning,” as the study characterizes this kind of movement, is little studied, but extremely common in U.S. schools. Teachers can switch to a different grade level, as often happens in elementary school. They can switch to teach a different content area if they have more than one license. And in high school, teachers bounce back and forth between AP classes and electives, and those in the general curriculum.
The new research study is among the first to provide some preliminary evidence that this churn, though probably unavoidable to some degree, on average isn’t doing students any favors.
The study, forthcoming in Educational Evaluation and Policy Analysis, was written by Allison Atteberry of the University of Colorado Boulder, Susanna Loeb of Stanford University, and James Wyckoff of the University of Virginia.
For the study, they looked at records on teachers in New York City all the way back from 1974 through 2010. A subset of those teachers, from 1999-2000, were linked to student achievement records in grades 3-8, allowing the researchers to analyze the link between teacher churn and students’ test scores.
Let’s take a look at the findings.
How common is teacher churn?
In New York City, pretty common: Overall, the study found, between 1974 and 2010, nearly 42 percent of teachers have new assignments in some way during a typical school year. Of that 42 percent,
- 15 percent of them are new teachers;
- 6 percent are new to New York schools (but not to teaching);
- 25 percent are moving schools; and
- a whopping 54 percent are changing assignments in the same school.
What this means is that a NYC student is about four times more likely to be taught by a teacher who changed grade levels or subjects within a school, than to be taught by a teacher new to teaching.
What’s driving teacher churn in New York City?
Much of it seems to be caused by teachers who leave a school or the profession, thereby requiring administrators to shuffle teachers around and hire new ones to make sure all classes are covered. But that’s not the only reason: Some schools tended to have far more switches than others.
Does “churn” affect some students and teachers more?
Dozens of studies show that needy students and students of color tend to get less qualified and effective teachers. The study shows that, in NYC, black, Hispanic, and English-learner students were somewhat more likely to be assigned to a teacher moving to a new grade or subject in his or her school, but the overall difference was small.
Similarly, while there was some evidence that some teachers—novices, teachers of color, male teachers, and those with low “value added” scores—are more likely to to be reassigned both within and between schools, most of the differences were small.
Does churn affect student learning?
Yes. Across all the different kinds of churn—new to teaching, new to New York City, new to a school and new to a grade—switching tended to lower student achievement. The magnitude differed depending on the type of switch, though. Not surprisingly, switching both a subject and a grade tended to be more difficult than just switching one or the other.
“The results suggest that the more aspects of one’s subject-grade-school assignment are unfamiliar, the more negative the impact of the reassignment,” the authors wrote.
As for magnitude, the researches estimated that getting a churned teacher is about a quarter of the size of being assigned a brand new teacher. So while not huge, the fact that it’s common means that over time, churn can add up to lost learning for students.
But don’t some teachers end up happier—and more effective‐in their new placements?
It’s a good theory, but the study indicates that most switches don’t end up matching teachers to assignments that make them more effective.
Does this pattern exist outside of New York City?
It’s hard to say, because New York City is such a unique district with such a large teaching force, and transfer rules and so on differ from place to place. Just within New York state, the researchers found that the average within-school switch rate is 15 percent; the city’s is 22 percent. Certainly some additional research could help flesh out whether this occurs in districts outside of New York.
Should schools take steps to prevent churn?
Well, the authors note that “it is an unavoidable artifact of such a large system that instability can and will occur.” But, they note, if the pattern is found in many other districts, then it might be worth administrators’ sitting down and trying to minimize students’ “doses” of churn as they progress through school.
For more on teacher assignments:
A version of this news article first appeared in the Teacher Beat blog.