The purpose of this investigation was to extend our knowledge of the effects of small classes in the primary grades on pupils’ academic achievement. Three questions were addressed that have not been answered in previous research: (1) How large are the effects of small classes relative to the number of years students participate in those classes? (2) How much does any participation in small classes in K–3 affect performance in later grades when all classes are full-size? (3) How much does the duration of participation in small classes in K–3 affect the magnitude of the benefits in later grades (4, 6, and 8)? Rationales for expecting the continuing impacts of small classes were derived in the context of other educational interventions (for example, Head Start, Perry Preschool Project). The questions were answered using data from Tennessee's Project STAR, a statewide controlled experiment in which pupils were assigned at random to small classes, full-size classes, or classes with a full-time teaching assistant. Hierarchical linear models (HLMs) were employed because of the multilevel nature of the data; the magnitude of the small-class effect was expressed on several scales including “months of schooling.” The results for question (1) indicate that both the year in which a student first enters a small class and the number of years (s)he participates in a small class are important mediators of the benefits gained. The results for questions (2) and (3) indicate that starting early and continuing in small classes for at least three years are necessary to assure long-term carryover effects. Few immediate effects of participation in a class with a full-time teacher aide, and no long-term benefits, were found. The results are discussed in terms of implications for class-size reduction initiatives and further research questions.

This investigation addressed 3 questions about the long-term effects of early school experiences: (a) Is participation in small classes in the early grades (K-3) related to high school graduation? (b) Is academic achievement in K-3 related to high school graduation? (c) If class size is related to graduation, is the relationship explained by the effect of participation in small classes on students' academic achievement? The study included 4,948 participants in Tennessee's class-size experiment, Project STAR. Analyses showed that graduating was related to K-3 achievement and that attending small classes for 3 or more years increased the likelihood of graduating from high school, especially among students eligible for free lunch. Policy and research implications are discussed.

Despite more than 600,000 teacher aides in American schools today, research provides little information about their classroom activities, their qualifications for carrying out their duties, or their impact on student achievement and behavior. This investigation asked whether the presence of a teacher aide in the classroom has any noticeable impact on pupils' learning. Three primary questions were addressed: (1) In Grades K through 3, does the presence of a full-time teacher aide in the classroom affect students' academic achievement? (2) If teacher aides have a positive effect on students' performance, does the effect depend on the number of years the student attends classes with a teacher aide? (3) Do some functions of aides (i.e., clerical tasks, instructional tasks, noninstructional tasks) have a greater impact on student achievement than others? This investigation showed that the teacher aide movement in the United States has created a state of affairs that requires many aides to perform tasks for which they are ill-prepared. In addition, teacher aide data were analyzed from Tennessee's Project STAR, a longitudinal experiment in which students were assigned at random to small classes, regular-size classes without an aide, or regular-size classes with a full-time teacher aide. The analyses reported here extend previous investigations, examining the functions and effects of teacher aides in depth. The results showed that teacher aides have little, if any, positive effect on students' academic achievement. The only positive effect was an improvement in reading scores for students who attended a class with a teacher aide for 2 or 3 years. These results were the only exceptions to a plethora of negative findings. The study also showed that the types of duties aides performed had no bearing on student achievement. Because teacher aides are called upon increasingly to provide instruction to pupils, policies and research must help us select and prepare aides to perform effectively.

The purpose of this investigation was to extend our knowledge of the effects of small classes in the primary grades on pupils’ academic achievement. Three questions were addressed that have not been answered in previous research: (1) How large are the effects of small classes relative to the number of years students participate in those classes? (2) How much does any participation in small classes in K–3 affect performance in later grades when all classes are full-size? (3) How much does the duration of participation in small classes in K–3 affect the magnitude of the benefits in later grades (4, 6, and 8)? Rationales for expecting the continuing impacts of small classes were derived in the context of other educational interventions (for example, Head Start, Perry Preschool Project). The questions were answered using data from Tennessee's Project STAR, a statewide controlled experiment in which pupils were assigned at random to small classes, full-size classes, or classes with a full-time teaching assistant. Hierarchical linear models (HLMs) were employed because of the multilevel nature of the data; the magnitude of the small-class effect was expressed on several scales including “months of schooling.” The results for question (1) indicate that both the year in which a student first enters a small class and the number of years (s)he participates in a small class are important mediators of the benefits gained. The results for questions (2) and (3) indicate that starting early and continuing in small classes for at least three years are necessary to assure long-term carryover effects. Few immediate effects of participation in a class with a full-time teacher aide, and no long-term benefits, were found. The results are discussed in terms of implications for class-size reduction initiatives and further research questions.