What does Piaget's theory primarily measure in children's development?

Piaget's theory primarily focuses on the cognitive processes involved in children's development. Jean Piaget was a Swiss psychologist who proposed a theory of cognitive development that describes how children acquire knowledge and the mental processes they use as they grow. His theory outlines distinct stages of cognitive development: sensorimotor, preoperational, concrete operational, and formal operational. Each stage represents a different way of thinking and understanding the world.

The emphasis is specifically on how children construct their understanding through experiences and interactions with their environment. Key aspects measured in his theory include how children think, reason, solve problems, and perceive reality. This is opposed to physical growth, social skills, or emotional responses, which might be studied in other developmental theories, but are not the focus of Piaget's work on cognitive development. Thus, the choice that highlights cognitive processes aligns perfectly with the essence of Piaget's contributions to understanding child development.