This paper examines teachers' preexisting notion of the "weak" academic student, and the characteristics implicit in that stereotype. Extant literature demonstrates how the teacher's dichotomous conceptions of "strong" and "weak" academic students are predictive of scholastic success. The goal of this study was to demonstrate how teachers' implicit assumptions of students' scholastic failure become transformed into concrete attributions when the teachers are asked to explain students in a failure situation. Invited to complete a questionnaire assessing the potential causes of their students' scholastic failures were 370 teachers. Results show how teachers' conceptions of students as either "strong" or "weak" academically creates a "cognitive brake" on student scholastic achievement. (Contains 2 tables.)