Two instructional methods were identified and compared to determine if any significant differences could be noted on three criterion measures. Measurements were conducted in the areas of achievement in biology, science attitudes, and critical thinking ability. Student ability was measured using pre-tests and the Scholastic Aptitude Test. Students were additionally evaluated relative to the factors of sex and socio-economic status. The post-test versions of the Nelson Biology Test, the Allen Attitude Scale and the Watson-Glaser Critical Thinking Appraisal were administered as criterion measures for use in comparison and in testing of the null hypotheses. Using a one-way analysis of covariance to compare, no significant differences on the criterion variables related to attitude and critical thinking ability were found. A two-way analysis of covariance combined with a regression analysis indicated no significant differences between the groups concerning the factors of sex and socio-economic status relative to achievement on the criterion measures. (Author/EB)