The effects of the type of earth science course (Earth Science Curriculum Project (ESCP) and non-ESCP), the directness or indirectness of teacher-pupil interaction in various teaching activities (I/D ratio), and the teacher's philosophical orientation (T/NT ratio) on various student outcomes such as understanding of science and scientists; critical thinking; knowledge of physical and natural science facts, and knowledge of principles, methods, and procedures of science were studied. Thirteen Iowa schools, 17 teachers, and 750 students were involved in the study. Six tests were used to measure student outcomes. Factors compared with the ESCP and non-ESCP students were the teacher's average I/D ratio, laboratory I/D ratio, discussion I/D ratio, teacher's philosophical orientation. Flander's Interaction Analysis was used to determine I/D ratios, and a Teacher's Educational Credo Preference Check List was constructed to determine the T/NT ratio. Some of the findings were: (1) the ESCP students develop into significantly better critical thinkers than the non-ESCP students, (2) a student with a teacher having direct and traditional beliefs has an advantage if in a non-ESCP course and is at a disadvantage if in an ESCP course, (3) a student having a teacher that is indirect with non-traditional beliefs has an advantage if in an ESCP course and is at a disadvantage if in a non-ESCP course. (BC)