How does cognitive development occur? Many attempts have been made to accurately describe children's cognitive development, and one of the most widely used is Jean Piaget's theory. According to Piaget, children go through a series of four stages of cognitive development. In this assignment, you will use a scenario to explain Piaget's four stages of cognitive development. Imagine you are going to make cookies with the help of four children. Charlie is 2 years old, Penelope is 6, Isabelle is 9, and Brian is 11.