The Formation and Stability of Instructional Groups

This paper argues that structural and organizationalfactors affect the formation and stability of ability groups in an elementary classroom which in turn affect growth in academic achievement. Empirical evidencefrom reading and mathematics groups in a sample of 48 classes shows that structural constraints deter the creation of small, homogeneous ability groups for instructional purposes. Ability groups are found to be fairly large in size and stable over the school year. Ability grouping is seen to increase the variance in the achievement distribution of a class, implying greater inequality in educational attainment in grouped classes.