Study Shows Larger Classes With Effective Teachers Improves Student Achievement

A new study released by the Thomas B. Fordham Institute found that placing more students in the classrooms of highly effective teachers can improve student achievement. The study, by Michael Hansen of the American Institutes for Research, simulates the impact on student achievement if schools were to purposely assign larger classes to the strongest teachers and smaller classes to the weakest.

The study, Right-sizing the Classroom: Making the Most of Great Teachers, concludes that schools can achieve significant student achievement gains if they place more students in the classrooms of highly effective teachers and fewer students in classrooms of less effective teachers.

The study examines longitudinal data in grades four through eight from North Carolina across four school years, from 2007–08 through 2010–11. The study was funded by the Searle Freedom Trust and the Thomas B. Fordham Foundation.

In the eighth grade, assigning up to 12 more students than average to effective teachers can produce gains equivalent to adding two-and-a-half extra weeks of school. These gains are seen for all students, not just those who moved classrooms, according to the study.

In the eighth grade, the study showed that three-fourths of the potential gain from allowing up to 12 students to be assigned to the best teachers’ classes can be realized when allowing just six students to move.

The study also showed that adding up to six more students than the school’s average produces math and science gains akin to extending the school year by nearly two weeks; and the potential gains from moving students to the most effective eighth-grade teachers are comparable to the gains seen by removing the lowest 5% of teachers.

According to researchers, gaps existed in students’ access to effective teaching. Specifically, economically disadvantaged students in eighth grade are 8% less likely than non-disadvantaged peers to be assigned to a teacher in the top 25% of the performance rankings.

This is primarily because the pool of available teachers in high-poverty schools remains unchanged under this strategy. Hence, this policy alone won’t remedy achievement gaps.

Michael J. Petrilli, executive vice president of the Fordham Institute, said “this is a simple change that can yield significant academic-achievement gains. Now it’s time for a district or state to implement this in real classrooms.”

Evaluating teacher effectiveness continues to be a hot issue nationwide, as different states have progressed at different rates with defining an effective teacher, assessing staff and implementing changes based on the results. The Delaware Department of Education recently asked its school principals to be tougher on evaluations of teachers. The Department raised concerns after only 1% of teachers were rated ineffective.

The education department reported that, during the first full year of the state’s evaluation system, only 1% of the state’s teachers were rated ineffective. State officials said it seems that school leaders aren’t making the tough evaluations needed to give honest feedback and eliminate low-performing teachers.