Answer:
The theory was proposing that children progress through different stages of cognitive development
Explanation:
Jean Piaget was a Swiss psychologist. He was a famous psychologist worked on child development. In his theory, he describes how children construct their mental model about the world. He never agreed with the concept that intelligence is fixed traits. He focused on the cognitive development of the children that occurs due to the combination of biological and environmental factors. He was the first psychologist who studied a systematic way of development of the children.
