Ability Grouping and Student Learning

Many school practices and policies are built on the assumption that students learn best when the curriculum is well matched to students' learning abilities. The belief is that when students understand what they are being taught, they are more likely to be actively involved in the learning process and less likely to disengage from classroom instruction and activities. The common practice of age-grading, which assumes that student age correlates with learning ability, enables teachers to present a curriculum designed to interest and challenge students at a particular age. Similarly, the practice of curriculum differentiation found in most secondary and middle schools and some elementary schools is based on this belief. Teachers assign students to ability groups to ensure that the curriculum they receive is suitable for their academic preparation and to expose them to new material at a level that they can comprehend.

Ideally, ability grouping should maximize student learning. In practice, ability grouping falls far short of its goal. Limitations in the process of assigning students to ability groups and in the pedagogical techniques utilized at different ability group levels seriously restrict the learning opportunities that are provided to students in some ability groups.

Empirical research reveals several of the limitations in the practice of ability grouping that account for its failure to maximize learning opportunities for students. Studies show that the criteria schools use to assign students to ability group levels do not always produce groups that are homogeneous with respect to ability. Schools generally rely on some combination of standardized test scores, grades, teacher and counselor recommendations, student and parent choice, and college and vocational requirements to assign students to ability groups. This implies a certain subjectivity in the assignment process and leaves open the possibility that nonacademic factors may play a significant role in determining the ability group level to which a student is assigned. To the extent that this is the case, a student may be placed in an ability group that has a curriculum that is easier or more difficult than the student's learning level. That is, the assignment process may produce a poor match between student learning ability and the curriculum to which the student is exposed. As a result, the student may not learn as effectively or efficiently as would occur in a different level group.

Empirical research also shows that, on average, students assigned to higher-ability groups attain higher test scores than those placed in lower groups. Both survey and observational studies suggest reasons for this ability group effect. Studies show that students in higher-ability groups are given higher-quality instruction, a more challenging and interesting curriculum, and more teaching time than those in lower-ability groups. Further, students in high-ability groups are immersed in a more academic climate, are more academically minded, and attain higher social status than those in lower-ability groups. These characteristics of ability groups increase learning opportunities for the students assigned to them. In contrast, the research suggests that students in low-ability groups are offered a less challenging and less interesting curriculum, are assigned more boring academic tasks, have less experienced teachers and fewer academic role models, and endure a more disruptive classroom atmosphere. As a result, they are offered fewer opportunities to learn.

While a negative effect of ability grouping on the achievement of students assigned to lower-ability groups has been noted frequently, no empirical research has looked at the effect on academic achievement of moving a student from one ability group level to a higher or lower group. This paper reports on an empirical study that demonstrates that students would generally attain higher test scores if they were moved to a higher-ability group than if they remained in the one to which they were assigned. Conversely, they would perform more poorly if moved to a lower-ability group. What is remarkable about this finding is that...