Study: Best Teachers Should Have the Largest Classes
(CNSNews.com) – Contrary to the practice of school districts nationwide, assigning more students to the best teachers, and less students to the lowest-performing instructors, would significantly boost student test scores, according to a recent study that concludes that the “magnitude of differences" between the best and worst teachers “swamps the expected effect of smaller classes.”
“One simple change—giving effective teachers a handful more students—could mean a big boost to student achievement,” labor economist Michael Hansen concluded in the study, entitled “Right-sizing the Classroom: Making the Most of Great Teachers,” he conducted for the Thomas B. Fordham Institute. (See class size.pdf)
Although educators have mixed views on the importance of class size, the conventional wisdom is that smaller is better. Hansen disagrees.
“Instead of trying to keep class sizes small, we should be leveraging our existing teacher talent by enlarging the classes taught by our best instructors – and compensating these excellent teachers for the extra work involved,” he says.
“Part of the appeal of this strategy is that it is a way of paying outstanding teachers more— under the cover of giving them more students,” he added.
Hansen, a senior researcher at the American Institutes for Research (AIR), used actual classroom data from North Carolina, a state in which only “25 percent of students are taught by the top 25 percent of teachers,” to simulate what would have happened if top-performing teachers had been assigned more students.
State laws, district policies, and bargaining agreements prevent most school districts from following this approach. However, after analyzing three years of fifth and eighth grade test scores, Hansen’s simulation found that assigning an additional 12 students to the best fifth grade teachers - up to a maximum of 32 students in the classroom - made little difference, adding the equivalent benefit of just two extra school days.
However, test scores in eighth grade jumped when the most effective teachers were assigned 12 more students, producing gains “equivalent to adding two-and-a-half extra weeks of school.”
Just shifting six students would also make a significant difference, Hansen noted, adding that “no district to my knowledge has purposefully allocated students in this manner.”
“The simulated gains in eighth-grade math and science achieved by shifting just six additional students to effective teachers are equivalent to the expected effect of removing the lowest 5 percent of teachers in these subjects—and these gains can be achieved without actually removing them!”
Students remaining in the lower-performing teachers’ classes would also benefit, the study found.
“The ‘shifted’ students benefit from being reassigned to a better teacher, and their gain exceeds the ‘penalty’ imposed on other pupils already in that classroom who now have a slightly larger class. What’s more, the remaining students in the less-effective teacher’s class receive a ‘benefit’ because their class becomes smaller.”
Although Hansen acknowledges that small classes are “wildly popular,” and that “there is some evidence they boost student achievement,” he points out that “it would take an increase of at least ten to twenty additional students in a good teacher’s class to dilute his productivity to that of an average teacher.”
Therefore, he concludes, “universally shrinking class sizes may be counterproductive in terms of pupil achievement.”
He also cited a 2012 survey by the Farkas Duffett Research (FDR) Group that found that 73 percent of parents would pick a class with 27 students taught by one of the best teachers in the school district for their child over a smaller class of 22 students taught by a “randomly chosen teacher.”
However, he warns that moving students to different teachers within the same school would have little effect on the minority achievement gap because “the pool of available teachers in high-poverty schools does not change under this strategy.”