Jean Piaget (1896-1980) always considered himself a natural scientist, not a psychologist. As a boy he quickly gave up play and pretend to take refuge in "work" -- exploring internal combustion ...

Piaget's theory divides this period into two parts: the "period of concrete operations" (7 to 11 years) and the "period of formal operations" (11 years to adulthood). According to Piaget, children's ...