Does Sorting Students Improve Scores?

This paper examines schools' decisions to sort students into
different classes and how those sorting processes impact student
achievement. There are two potential effects that result from
schools creating homogeneous classes--a "tracking effect," which
allows teachers to direct their focus to a more narrow range of
students, and a peer effect, which causes a particular student's
achievement to be influenced by the quality of peers in his
classroom. In schools with homogeneous sorting, both the tracking
effect and the peer effect should benefit high performing students.
However, the effects would work in opposite directions for a low
achieving student; he would benefit from the tracking effect, but the
peer effect should decrease his score.

This paper seeks to determine the net effect for low performing students
in order to understand the full implications of sorting on all students.


The paper uses a unique student-level data set from Dallas Independent School
District that links students to their actual classes and reveals the
entire distribution of students within a classroom. The authors find
significant variation in sorting practices across schools and use
this variation to identify the effect of sorting on student
achievement.

The authors find that sorting homogeneously by previous performance
significantly improves students' math and reading scores. This
effect is present for students across the score distribution,
suggesting that the net effect of sorting is beneficial for both high
and low performing students.

The paper also explores the effects of sorting along other
dimensions, such as gifted and talented status, special education
status, and limited English proficiency.