Teacher quality varies within schools, not just across them
Quality teachers are one of schools’ most important resources. Students assigned to higher-quality teachers learn more the year they are in class with that teacher as well as in subsequent years. Students assigned to higher-quality teachers are also more likely to graduate from high school, attend college, earn higher salaries, and live in more affluent neighborhoods, among other positive outcomes.
Given these potentially large teacher effects, it is concerning that schools vary considerably in the types of teachers they employ. The teacher labor market works to disadvantage urban schools, which often have difficulty attracting and retaining effective teachers. Schools with high concentrations of low-income, low-achieving and/or minority students tend to employ teachers with less experience, lower test scores, fewer advanced degrees, and teachers who attended less selective colleges. Therefore, students from more disadvantaged backgrounds are less likely to be exposed to experienced and highly qualified teachers compared to their more advantaged counterparts attending other schools.
In “Systematic Sorting: Teacher Characteristics and Class Assignments” authors Demetra Kalogrides, Susanna Loeb and Tara Béteille find that teachers are sorted within schools as well as between schools. The authors examine the average prior year test scores of students in teachers’ classes. They find that less experienced teachers are assigned classes with lower achieving students relative to their more experienced colleagues that teach in their grade and at their school. The differences are large-- teachers with 10 years of additional experience teach students that scored considerably higher (one-third of a standard deviation). Teachers who have held leadership positions and those who attended more competitive undergraduate institutions are also assigned higher achieving students than their colleagues at their school. These results are found at all grade levels, even in elementary schools.
These patterns of teacher assignment likely result from a complex process where school leaders attempt to respond to teacher, parent and organizational preferences. For example, principals may try to ‘reward’ experienced teachers that they wish to retain, or experienced teachers may hold more power in the school to achieve their own desires for the student composition of their classrooms.
Most of the policy discussion around the distribution of teachers focuses on reducing differences in average teacher quality across schools. Some policies, for example, offer financial incentives for teachers to enter or stay in harder to staff schools, particularly high poverty schools. However, within-school teacher sorting may undermine the effectiveness of such policies if the most experienced or effective teachers in these schools are assigned to the relatively least disadvantaged or highest achieving students. Moreover, within school sorting may be detrimental to schools’ overall effectiveness. Within school sorting may prevent the most effective teachers from being matched to students who need them most even if the sorting of teachers between schools is minimized.
The full study is here: Kalogrides, Demetra, Susanna Loeb and Tara Béteille, “Systematic Sorting: Teacher Characteristics and Class Assignments,” Sociology of Education, forthcoming.
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