International Evidence on Ability Grouping with Curriculum Differentiation and the Achievement Gap in Secondary Schools

Background/Context: The achievement gap between students from different backgrounds is an issue of grave concern in the United States and in many other developed countries. U.S. research suggests that tracking and other forms of ability grouping with curriculum differentiation may be implicated in increasing this gap. Unfortunately, U.S. researchers often neglect the increasingly rich and methodologically sophisticated literature from other developed countries related to this topic. Purpose/Objective: This article brings readers' attention to a wide variety of high-quality research that is commonly underused by U.S. scholars interested in the origins of the achievement gap. It does this by reviewing what research from other developed countries says regarding two fundamental questions addressed by U.S. researchers: (1) Is having higher achieving schoolmates/classmates commonly associated with larger achievement gains for secondary school students? and (2) Is ability grouping with curriculum differentiation commonly associated with a larger achievement gap for secondary school students? This article explores the latter question in ways not typically possible in the U.S. Specifically, it asks: (a) Do hierarchical tiered educational systems, which provide separate schools with markedly different curricula for students with different abilities and career aspirations, increase the achievement gap? and (b) Do school systems that have relatively large amounts of ability grouping with curriculum differentiation or that start this practice early have a larger achievement gap than others? Research Design: A narrative literature review was conducted focused on the preceding questions. High-quality research typically (a) conducted in secondary schools in other developed countries, (b) authored by researchers outside the United States, and/or (c) published in non-U.S.-based sources is highlighted. Conclusions/Recommendations: International research supports the conclusion that having high-ability/high-achieving schoolmates/classmates is associated with increased achievement. It also suggests that ability grouping with curriculum differentiation increases the achievement gap. For example, attending a high-tier school in a tiered system is linked with increased achievement, whereas attending a low-tier school is linked with decreased achievement, controlling for initial achievement. Furthermore, there is a stronger link between students' social backgrounds and their achie