The purpose of this study was to determin the effects of an individualized instruction approach and a teacher centered approach on student achievement of science content and problem solving skills, science interest, and self concept. Eighty-one fifth grade pupils were divided into three classes of 27 each: a teacher-centered active control group, an individualized experimental group both taught by the researchers, and a teacher-centered passive control group taught by their classroom teacher. Course content was based on "Today's Basic Science" and AAAS Science - A Process Approach. Among the findings were (1) that the individualized method of instruction did not prove superior to the teacher-centered approach in achievement of science content, overall problem solving ability, increased science interest, or the attainment of a more positive self concept, and (2) that the teacher-centered program stressing problem solving as its major objective was significantly more effective in achieving the ability to identify valid conclusions than both the individualized program and the teacher-centered passive program. (GR)