Tennessee's Student/Teacher Achievement Ratio project (Project STAR) was designed to study the effects of class size on pupils in primary (K-3) grades. Responses of Project STAR teachers (N=1,003) to the annual Teacher Exit Interview are summarily reported for 1986 through 1989. Generally, the perceptions of teachers in small classes, in regular size classes of about 25 pupils, and in regular size classes with an aide were highly consistent from grade level to grade level. Teachers of small classes explained how their teaching had differed in relation to having only 13 to 17 children, whereas teachers of regular size classes with an aide explained how having a full-time teacher's aide accounted for the differences they experienced. After background and methodological information, contents concern: (1) time and instruction; (2) individualizing instruction; (3) the learning environment in small and regular size classes with aides; (4) conclusions from Project STAR teacher interviews; (5) grouping practices of Project STAR teachers; (6) interaction of teachers with parents and volunteers; (7) teachers' perceptions of work-related problems; and (8) effects of class size reduction and use of full time teacher aides on classroom processes and teacher behaviors. (RH)