Two Biological Sciences Curriculum Study (BSCS) approaches to teaching high school biology were employed to study the relative effects which different curriculum approaches might have on certain intellectual aptitudes of students. Subjects included 144 students enrolled in the BSCS Yellow Version and 143 students enrolled in BSCS Blue Version. Identification batteries consisting of seven cognitive factor tests chosen from the "Kit of Reference Tests for Cognitive Factors" were administered to the students as a pretest and as a post-test following a year's biology instruction. The BSCS Comprehensive Final was also give n at the end of the year's instruction. Concluded were that (1) cognitive aptitude did change over the course of BSCS instruction; (2) for the three factors--Induction, Flexibility of Closure, and Syllogistic Reasoning--the BSCS Blue Version approach affected cognitive change to a greater degree than did the Yellow Version approach; (3) the extent to which the aptitudes measured by the factor tests were correlated with performance on the BSCS Comprehensive Final was greater for Blue Version students than for those of the Yellow Version. (RS)