All those services whose main function is (1) to inspect, control, evaluate; and/or (2) advise, assist, and support school heads and teachers.
De Grauwe, Anton, Carron, Gabriel. 2011. Supervision: A Key Component of a Quality Monitoring System - Module 1 - UNESCO. Paris: UNESCO-IIEP.
One of the main roles of any school supervision system is to monitor the quality of education, i.e. of schools and teachers. This monitoring is expected to have a positive impact on their quality. As such, supervision forms part of an overall quality monitoring and improvement system, which includes other devices such as examinations and achievement tests, and self-assessment practices by school and teachers (UNESCO-IIEP, 2011:3).
De Grauwe, Anton, Carron, Gabriel. 2011. Supervision: A Key Component of a Quality Monitoring System - Module 1 - UNESCO. Paris: UNESCO-IIEP.