Lev Vygotsky, a Russian psychologist, developed a theory of cognitive development known as the Sociocultural Theory of Cognitive Development in the early twentieth century.The main assertion of the Vygotsky theory is that the cognitive development of children is advanced through social interaction with other people, particularly those who are more skilled. In other words, Vygotsky believed that social learning comes before cognitive development, and that children construct knowledge actively.
Social Development Theory (Lev Vygotsky) – InstructionalDesign.org