Piaget theory is a major development theory. Another Development theory that focus on children's cognitive is vygotsky's theory. their cognitive development depends on the tools provided by society and their minds are shaped by the cultural context in which they live. The zone of proximal development:- vygotsky's ZPD has a lower limit and an upper limit. Tasks in the ZPD are too difficult for the child to perform alone. They require assistance form an adult or a skilled child. As children experience the verbal instruction or demonstration, they organise the information in their insisting mental structures. Scaffolding: - In cognitive development vygotsky used this term to describe the changing support over the course of a teaching session, with the more skilled person adjusting guidance to fit the child's current performance level. language and thought:- The use of dialogue as a tool for scaffolding is only one example of the important role of language in a chi