The document discusses the social system of schools. It defines a social system as (1) a group of interacting elements that form a unified whole, and (2) activities and interactions of groups brought together for a common purpose. Schools are described as social systems characterized by interdependence, a defined population, and differentiation from the environment. Key elements of schools as social systems include structure, individuals, culture, politics, a technical core (teaching and learning), the environment, outputs, feedback, and effectiveness.