The central concern of this study, which was briefly reviewed in ED 049 143, was to determine effective teaching strategies and practices in secondary social studies classroom discussions of social issues. Teaching effectiveness was evaluated in terms of the cognitive or critical thinking skills of participating students, and their attitudes toward the teacher and class. Incidently, the affective side effects of social issues instruction are reported separately in ED 039 162. In the initial analysis of two audio-taping sessions for each of sixteen classes it became apparent that distinct discussion styles existed: 1) expository, sharing background information only; 2) inquiry-nonprobing, giving hypotheses, opinions, and taking positions only; and, 3) inquiry-probing, developing ideas as well as devoting much time to defining, clarifying, evidencing, or testing these ideas. The instruments used for ascertaining the students critical thinking skills were the Michigan Social Issues Cognitive Category System, developed by the project as reported in ED 039 161, and the Harvard Social Issues Analysis Test; to determine student attitudes, the Minnesota Student Attitude Inventory was used. Students in the probing classes rated their classes highest and did very well on the critical thinking test; the expository classes came next, followed by the nonprobing classes with the lowest ratings and test scores. (Author/SBE)