The Effect of School Size and the Interaction of School Size and Class Type on Selected Student Achievement Measures in Tennessee Elementary Schools

The purpose of this study was to analyze student academic achievement in reading and mathematics for grades K through 3 to determine if there was a school-size effect. This study further analyzed whether the school-size effect differed across the three class types: small (S), regular (R), and regular with aide (RA), to which students had been assigned. Several null hypotheses were posited regarding the effect of school size and interaction of the school-size effect with each of the three class types on the academic achievement of students. This study of school size benefited from having an extant database of information on over 7,000 students with random assignment of students and teachers to classes within each school. These students were randomly selected and heterogeneously assigned to three class types based on an average teacher-student ratio: S=1:15, R=1:25, RA=1:25. This study employed correlation, t -test, and other appropriate statistical tests to determine any effect of school size and the interaction of school size and class type. The class was used as the unit of analysis for both the school-size and class-type effects. The extant database used to conduct this study was developed from a statewide, longitudinal study of the effect of class type on student achievement (Project STAR) within 79 elementary schools in 42 Tennessee public school systems during 1985-89. At the end of the longitudinal study 76 schools remained in the database. The class-type study utilized a within school research design with the class as the unit of analysis. This allowed for control of individual teacher effects and other contextual variables (e.g. school leadership, curriculum, instructional materials, and expenditures). The class-type study found that the S class type has a positive, statistically significant (p≤.001) and educationally important effect (effect size from .22 to .44) on student achievement for grades K through 3 (Word et al., 1990). The null hypotheses of this study on school size were not supported. The study found that the negative relationship between school size and the academic achievement of students reported in the research literature was evident in the extant database. The negative effect of large school size differed for the three class types and by school location. The negative effect of large school size on student achievement in all three class types was most evident for inner-city schools School size did not have a significant effect on student achievement in rural schools. The S class type produced the highest student achievement of the three class types except in small rural schools where the RA class type produced the highest student achievement. The S class type countered the negative effect of large school size on student achievement better than the RA class type. Overall, the study findings indicated that small school size was more important to student achievement in mathematics and the S class type was more important to student achievement in reading. School size alone did not appear to account for the negative effect of large schools on student achievement. The negative effect of large school size on student achievement in both reading and mathematics for all three class types became more evident as students progressed in school during grades K through 3