Mary Cassatt (1844-1926) was a American painter known for her paintings of mothers and children. The document discusses Jean Piaget's four stages of cognitive development in children: sensorimotor stage (birth to 2 years), preoperational stage (2 to 7 years), concrete operational stage (7 to 11 years), and formal operational stage (11 years into adulthood). It provides examples of the types of behaviors, thoughts, and reasoning abilities typical of children at each stage of development.