Abstract: | An educational application inspired by social constructivism, such as can be found in the theories of Vygotzky (1962, 1978) and Piaget (1925), was attempted, in order to improve the academic achievement of children studying in a heterogeneous class. A MANOVA analysis based on a study of 1046 pupils (8 to 11 years old, studying in 36 classrooms) shows that teaching within the framework of a cooperative learning program named ‘Complex Instruction’, when compared to frontal instruction, improves academic achievement, especially that of lower level children. Improvement seems to be primarily the result.of students’ verbal interaction, while non‐interaction is either not related or related negatively. |