Whose theory suggests that intelligence changes as children grow?

Piaget's Theory

Jean Piaget's theory of cognitive development suggests that intelligence changes as children grow. A child's cognitive development is not just about acquiring knowledge, the child has to develop or construct a mental model of the world.

Cognitive development occurs through the interaction of innate capacities and environmental events, and children pass through a series of stages. Piaget's stages are:

Sensorimotor stage: birth to 18-24 months

Preoperational stage: 2 to 7 years

Concrete operational stage: 7 to 11 years

Formal operational stage: ages 12 and up

The sequence of the stages is universal across cultures and follow the same invariant (unchanging) order. All children go through the same stages in the same order (but not all at the same rate).