Jean Piaget (1896–1980) was a biologist who took an interest in studying the cognitive development of children. Piaget carried out many studies and he concluded that children were not less intelligent than adults; they merely have different thought processes. Piaget's theory has had a huge impact on psychology and educational theory today. Piaget developed four stages of cognitive development.
The Sensori-motor Stage (0-2 Years)
During the sensori-motor stage young children explore and investigate their surroundings using their five senses. Babies begin to develop schemas. Children are able to make things happen, such as shaking a rattle to make noise. At some point in this stage children will develop object permanance; knowledge that an object continues to exist when not in sight.
The Pre-Operational Stage (2-7 Years)
Children in the pre-operational stage are ego-centric; they are unable to see things from a point of view other than their own. Children are able to use language to represent objects by drawings and words. They are only able to classify objects into one category. (E.g. Children may arrange all blocks by colour regardless of shape.)