This article describes the Biology Critical Thinking (BCT) project in which carefully designed activities for developing specific critical thinking skills are incorporated into the biology curriculum. The objectives were to find out whether the BCT project contributes to the development of critical thinking skills in various biological and nonbiological topics and how it affects students' biological knowledge and classroom learning environment. The study consisted of 678 seventh graders who were assigned randomly into two groups that studied the same seventh‐grade biology textbook. Only one group, the experimental, completed the BCT activities. The results indicate that the students in the experimental group improved their critical thinking skills compared to their own initial level and compared to their counterparts in the control group. Improved critical thinking skills were observed in a new biological context and nonbiological everyday topics, suggesting generalization of thinking skills across domains. The experimental students scored significantly higher than the control on a knowledge test, suggesting that “knowledge of facts” as one educational goal and “learning to think” as another, need not conflict, but rather can interact with each other. Finally, the results show that BCT involvement decreased the frequency of teacher‐centered teaching and enhanced student‐centered, more active learning.

The purpose of this study is to investigate two issues related to the teaching of thinking skills: (1) transfer across domains; and (2) comparison between individual learning of a thinking strategy and ‘class‐like’ setting, which consists of a didactic intervention that takes place in small groups. A microgenetic design was used, in which community college students engaged in investigation of problems (each student participated in 20 sessions). It was found that: (1) the control of variables strategy that was taught in the context of a problem in one domain transferred fully to a new problem in the same domain, hut transferred less well to an isomorphous problem in a different domain; (2) the ‘class‐like’ setting contributed to improved performance (as measured by the frequency of valid inferences), with the didactic intervention seeming to contribute to this improvement; and (3) the learning environment described in this study had a larger effect on ‘slower learners’ than on ‘faster learners’. It is proposed to teach for enhanced transfer by focusing explicitly on recognition of underlying logical structures of content‐rich contexts.