The effects of certain teaching methods upon the development of critical thinking skills, an understanding of science and scientists, and knowledge of subject matter were investigated. An analysis of covariance and rank correlation between teacher behavior patterns and particular student outcomes on the "Watson-Glaser Critical Thinking Appraisal, Form Zm,""Processes of Science Test, Form A," and the "Biological Sciences Curriculum Study Comprehensive Final Examination" were made. Eight teachers using the Biological Sciences Curriculum Study "Molecules to Man" were randomly selected from teachers using these materials in eastern Iowa. Teacher behavior was assessed by using the Flanders' Interaction Analysis Scale. The findings support the notion of the central importance of the classroom teacher in influencing student outcomes and that direct teachers can cause students to learn subject matter equally as well as indirect teachers. Other findings are also reported in the study. (BC)