Do teacher aides help or hurt student achievement? the role of teacher experience

Employment of teacher aides in U. S. public schools increased roughly six-fold since 1969. Yet randomized studies of aides find predominantly negative effects on student achievement. This study of public elementary schools in Oregon explores the role of teacher experience in the effectiveness of aides and finds a strong complementarity between aides and teacher experience. The complementarity explains two results of prior studies: negative effects for aides and positive effects primarily for early years of teacher experience. Without complementarity, the effect of aides is negative; with it, the effect is positive for schools with experienced teachers and negative only for schools with inexperienced teachers. Similarly, without complementarity, the effect of experience is negative; with it, the effect is positive for schools that use aides intensively and negative only for schools that do not. The study exploits the longitudinal, hierarchical structure of the Oregon data to estimate a hierarchical linear model with controls for both observed and unobserved influences on individual student achievement. A series of alternative specifications, including a nullification test of causality based on prior test scores suggest robustness for the estimates. Results of the study suggest that prior evidence for the effectiveness of aides is too pessimistic in the context of experienced teachers and that prior evidence for the effectiveness of teacher experience is too pessimistic in the context of schools that use aides intensively. The results also suggest that experienced teachers have expertise important to effective supervision of aides, particularly in schools where teachers are relatively inexperienced and aides are prevalent. Hence, attempts to address problems of large class sizes by adding aides are more likely to be effective in schools with experienced teachers.