quantities the way we do. Piaget's theory of cognitive development ends at the formal operational stage that is usually developed in early adulthood. It does not take into account later stages of adult cognitive development as described by, for example, Harvard University professor Robert Kegan. Lev Vygotsky Lev Vygotsky's theory is based on social learning as the most important aspect of cognitive development. In Vygotsky's theory, adults are very important for young children's development. They help children learn through mediation, which is modeling and explaining concepts. Together, adults and children master concepts of their culture and activities. Vygotsky believed we get our complex mental activities through social learning. A significant part of Vygotsky's theory is based on the zone of proximal development, which he believes is when the most effective learning takes place. The zone of proximal development is what a child cannot accomplish alone but can accomplish with the help of an MKO (more knowledgeable other). Vygotsky also believed culture is a very important part of cognitive development such as the language, writing and counting system used in that culture. Another aspect of Vygotsky’s theory is private speech. Private speech is when a person talks to themselves in order to help themselves problem solve. Scaffolding or providing support to a child and then slowly removing support and allowing the child to do more on their own over time is also an aspect of Vygotsky’s theory. Unlike Jean Piaget, who believed development comes before learning, Vygotsky believed that learning comes before development and that one must learn first to be able to develop into a functioning human being. Vygotsky's theory is different from Piaget's theory in four ways. Firstly, Vygotsky believed culture affects cognitive development more. Piaget thought that cognitive development is the same across the world, while Vygotsky had the idea that culture influences cognitive development. Secondly, under Vygotsky's beliefs, social factors heavily influence cognitive development. The environment and parents the child has will play a big role in a child's cognitive development. The child learns through the zone of proximal development with help from their parent. Thirdly, while Piaget considered thought as an important role, Vygotsky saw thought and language as different, but eventually coming together. Vygotsky emphasized the role of inner speech being the first thing to cause cognitive development to form. And fourthly, Vygotsky believed cognitive development is strongly influenced by adults. Children observe adults in