Many educators consider individual differences among pupils as a classroom problem and some try to reduce the problem by streaming. This paper presents an alternative approach, based on social constructivism, in which individual differences are taken as an important resource in enhancing learning in the classroom. The paper is based on a naturalistic study with two primary schools implementing many learning strategies with a social constructivist root. These include collaborative learning, peer scaffolding and portfolio assessment. The strategies were gradually introduced in the two schools through encouragement and support of the research team. The lessons using the new strategies were videotaped and the pupils' works were collected for analysis. To supplement, standardized tests developed independently were used to triangulate the qualitative study. Results show that the introduction of social constructivism has a significant impact on classroom practices, on interactions of pupils and on their level of active participation on learning. Qualitative analysis of pupils' work also shows promising results. The observed improvement in learning has further been confirmed by statistical analysis of standardized test results. The findings strongly argue the possibility to handling individual differences without resorting to streaming strategies