Vygotsky measured his 'zone of proximal development' in years. To do this, he needed a scheme of age periods, and a set of tasks that could diagnose the next age period without defining it. In this paper, we compare the age periods in his late lectures with Halliday's categories of logico-semantic expansion as used by three adolescent…

The author introduces some constructs that provide a linkage between the Piagetian theory of cognitive development and curriculum analysis: externalization and automatization; the intellective unconscious; and the logical substructure of the task. He then offers some examples of developmental analysis of secondary level curriculum materials.…

Maintains that a major theme in Lev Vygotsky's later research was concept formation or conceptual development in child development. States that Vygotsky argued that the acquisition of mature academic concepts forms the crowning achievement of adolescence. Argues that the view raises a number of criticisms. (CFR)