Editing Educational psychology (section)

====Jean Piaget====

[[Jean Piaget]] (1896–1980) was one of the most powerful researchers in of developmental psychology during the 20th century. He developed the [[theory of cognitive development]].<ref name="zimmerman2"/> The theory stated that intelligence developed in four different stages. The stages are the sensorimotor stage from birth to 2 years old, the preoperational state from 2 to 7 years old, the concrete operational stage from 7 to 10 years old, and the formal operational stage from 12 years old and up.<ref name="zimmerman2"/> He also believed that learning was constrained to the child's cognitive development. Piaget influenced educational psychology because he was the first to believe that cognitive development was important and something that should be paid attention to in education.<ref name="zimmerman2"/> Most of the research on Piagetian theory was carried out by American educational psychologists.