Tanner stages are a tool used by healthcare providers to evaluate development in puberty. They detail five specific stages of physical change in puberty, including genital, breast, and pubic hair ...

Piaget’s stages of development include sensorimotor, preoperational, concrete operational, and formal operational. While there is some criticism of them, they may help characterize child development.

Erik Erikson was a German psychologist who theorized that there's a specific psychological struggle that takes place through the eight stages of a person's life. These struggles, he believed, ...