Vitgotsky

Vygotsky was born in 1896 in Orsha, in the Russian Empire (today in Belarus). He was tutored privately by Solomon Ashpiz and graduated from Moscow State University in 1917. Later, he attended the Institute of Psychology in Moscow (1924–34), where he worked extensively on ideas about cognitive development, particularly the relationship of work that is still being explored.
The major theme of Vygotsky's theoretical framework is that social interaction plays a fundamental role in the development of cognition. Vygotsky (1978) states: "Every function in the child's cultural development appears twice: first, on the social level, and later, on the individual level; first, between people (interpsychological) and then inside the child (intrapsychological). This applies equally to voluntary attention, to logical memory, and to the formation of concepts. All the higher functions originate as actual relationships between individuals." (p57).
A second aspect of Vygotsky's theory is the idea that the potential for cognitive development depends upon the "zone of proximal development" (ZPD): a level of development attained when children engage in social behavior. Full development of the ZPD depends upon full social interaction. The range of skill that can be developed with adult guidance or peer collaboration exceeds what can be attained alone.
Vygotsky's theory was an attempt to explain consciousness as the end product of socialization. For example, in the learning of language, our first utterances with peers or adults are for the purpose of communication but once mastered they become internalized and allow "inner speech".
Vygotsky's theory is complementary to the work of Bandura on social learning and a key component of situated learning theory.
Because Vygotsky's focus was on cognitive development, it is interesting to compare his views with those of Bruner and Piaget .
http://tip.psychology.org/vygotsky.html