Final answer:
Onlooker play is a child's observational stage in Parten's play categories, where they learn by watching others engage in play without direct involvement.
Step-by-step explanation:
The concept of onlooker play refers to a category of play where a child observes others at play but does not engage in it themselves. It is a stage of social play development as characterized by Mildred Parten's six play categories. Onlooker play often occurs before a child begins to play directly with others, serving as a way for them to learn about social interactions and the rules of play through observation.
Correctly identifying this stage of play is significant because it echoes the underlying concept that play is an essential part of childhood learning and socialization. Through activities such as watching others, children begin to understand how others interact and how various roles come together, much like in Mead's example of roles in a restaurant leading to a collective dining experience.