Now we turn our attention to those factors that affect individual students in the classroom—the independent impact that a teacher can have on student achievement. Naturally, an individual teacher is influenced by decisions the school makes (decisions that include a guaranteed and viable curriculum, challenging goals, and feedback). However, the teacher-level factors addressed here are primarily a function of decisions made by individual teachers, including instructional strategies, classroom management, and classroom curriculum design.

Before the mid-1980s, studies of effective schooling tended to look at school-level factors only, that is, the school as having a unitary and consistent impact on student achievement. Good and Brophy (1986) warned of the consequences of this perspective:

Studies of large samples of schools yield important profiles of more and less successful schools, but these are group averages [original emphasis] that may or may not describe how a single effective teacher actually behaves in a particular effective school. Persons who use research to guide practice sometimes expect all teachers' behavior to reflect the group average. Such simplistic thinking is apt to lead the literature to be too broadly and inappropriately applied. (p. 588)