The aim of this study is to identify misconceptions of some 7th grade students about physical, chemical changes, and controlling students' logical thinking and reading comprehension skills, to compare effects of cooperative learning approaches to traditional teaching on their understanding of subject. Research was administered to 46 7th grade students in Gumushane-Taslica Vali Simsek and Cumhuriyet Primary Schools; and completed in four weeks in the first term of 2003-2004. As research design, pre-post-test control group design was used. In experimental group, lessons were taught with cooperative learning; however, in control group, with traditional approaches. MDYT, OAYT and FKDT were administered as pre-tests; and FKDT was re-administered in the end. According to FKDT results, misconceptions were identified and with the interviews applied to 12 students, students ideas on subject were investigated in detail. Controlling other factors, cooperative learning was found more effective than traditional teaching approach: on students' understanding the subject.