An Experimental Study of the Effects of Class Size

The study investigated the effects of four class sizes (16, 23, 30, and 37) on teachers’ expectations; the attitudes and opinions of participants (students and teachers); student achievement in reading, mathematics, composition, and art; student self-concept; and a variety of classroom process variables (e.g., teacher-pupil interaction, pupil participation, method of instruction). Teachers and students were randomly assigned to a class size in Grades 4 and 5. A total of 62 classes in three school districts in Metropolitan Toronto participated in the two-year study. Findings indicated that teachers had definite expectations of class size effects that subsequently were reported to be confirmed by their experience in the study. However, most other results failed to support teachers’ opinions. Few of the observed classroom process variables were affected by class size. Although students’ mathematics-concept scores were higher in size 16 than 30 or 37, there were no class size effects for the other achievement measures (reading, vocabulary, mathematics-problem solving, art, and composition) or for students’ attitudes and self-concepts.