The powerful impact of teacher expectations: a narrative review.

In a narrative review we investigated teacher beliefs that moderate teacher expectation effects. An extensive literature search revealed that only three researchers had systematically examined (in at least three studies) teacher beliefs' differences and consequent expectation effects for students. Babad explored teachers who believed stereotypical information about students and showed how that bias translated into teacher-student interactions. Highly biased teachers had large negative self-fulfilling prophecy effects on student outcomes. Overall, the difference in contrasts between high and low bias teachers (those who did not accept stereotypes) was = 0.92. Weinstein's research investigated teachers who believed all students should be treated similarly versus teachers who believed high and low achievers should be treated quite differently (low and high differentiating teachers). The average effect size of the differences between these teachers was = 0.85. Rubie-Davies examined the idea that some teachers believe that all students can make large gains (high class-level expectations) whereas others believe their students will make little progress (low class-level expectations); the average effect size difference between high and low expectation teachers was = 0.87. Hence, the review showed that effect size differences between these different teacher types were remarkably consistent, and all were large.