Instructional leadership is generally defined as the management of curriculum and instruction by a school principal. This term appeared as a result of research associated with the effective school movement of the 1980s, which revealed that the key to running successful schools lies in the principals' role. However, the concept of instructional leadership is recently stretched out to include more distributed models which emphasize distributed and shared empowerment among school staff, for example distributed leadership, shared leadership, and transformational leadership.