States and school districts have begun to focus on providing a more equitable distribution of teachers for disadvantaged and non-disadvantaged students. We examine the distribution of teacher effectiveness in the District of Columbia (DC) by measuring the teacher effectiveness gap, the average difference in teaching effectiveness—as measured by value added—faced by students eligible for a free or reduced-price lunch compared to ineligible students.

DC received a Race to the Top (RTTT) grant from the federal government to institute systematic reforms that would, among other goals, distribute teachers more equitably. One of the unique features of the DC school system is its reliance on a great variety of charter schools, which educate over forty percent of the students. Each charter operates an independent local education agency (LEA), alongside the largest LEA, the DC public schools (DCPS).

We measure teacher effectiveness gaps across teachers of grades 4-8 in math and reading/English language arts in DCPS and DC charter schools participating in RTTT. We examine how differential assignment of teachers to students affects the overall teacher effectiveness gap between and within LEAs. Thus, we separately measure (1) gaps that arise between LEAs, resulting from the distribution of teachers across DCPS and the various charter school LEAs in the local labor market for teachers, and (2) gaps that arise within LEAs, resulting from LEA- and school-level assignment policies of teachers to students. We do this by statistically decomposing the teacher effectiveness gap into gaps that may exist between and within LEAs. We also examine similar dynamics at a higher level: how gaps vary between and within wards (eight divisions of DC that vary by socioeconomic status).

To put teacher effectiveness gaps in perspective, we also compare teacher effectiveness gaps to gaps in student achievement between disadvantaged and non-disadvantaged students. This will suggest the degree to which a more equitable distribution of teachers might alleviate student test score gaps in DC.