Maintains that current research suggests that heterogeneous grouping is preferable. Reports on a study of a new mathematics curriculum using 600 students in 6 Dutch schools. Finds that students in heterogeneous classes taught with cooperative-learning techniques achieved more than students in traditional ability-grouped classrooms. (CFR)

Describes study that compared the achievement of high and low ability eighth-grade students working cooperatively during computer-based instruction. Homogeneous and heterogeneous grouping based on ability are explained, posttest results are analyzed, and implications for instructional design are discussed. (23 references) (Author/LRW)