Cooperative play: Cooperative play begins in the late preschool period. The play is organized by group goals. There is at least one leader, and children are definitely in or out of the group. When children move from a self-centered world to an understanding of the importance of social contracts and rules, they begin to play games with rules. Part of this development occurs when they learn games such as Follow the Leader, Simon Says, and team sports. Games with rules teach children the concept that life has rules that everyone must follow.