Children need to be with children.
These skills are naturally being learned at this age: Saying good bye to mom and dad for a few hours, entering a new environment with unknown people (school), taking turns, sharing, entering play with peers, following instructions and directions, cooperative and dramatic play, gaining coping skills, waiting for short periods of time, initiating play and activities, walking in line, sitting and singing in circle time, talking and listening, applying oneself to challenging activities.