The cognitive development of children according to Piaget are measured by the child's ability to reason.
J. Piaget's cognitive development studies describe that this is a period where the child's ability to develop their intelligence / reasoning is expanded as they interact with his environment.
Therefore, we can conclude that the age of a child can be inferred in what state his reasoning is and therefore his cognitive development.
Learn more here: https://brainly.com/question/6959305