This curriculum evaluation study involved a group of 989 twelfth-grade students who participated in a given curriculum for four years. Effects of interaction between curriculum and such variables as teachers' bias, type of school, sex of student, and specific subject matter taught as related to achievement were sought. Schools included city academic, rural-kibbutz, and agricultural. Students were divided into groups designated by the curriculum used. Of these, 408 were in the Biological Sciences Curriculum Study (BSCS) curriculum, using the Israeli-adapted Yellow Version. The second group of 581 students was the non-BSCS group. Fifty different teachers were involved and divided into two groups, the BSCS supporters and the non-supporters, based on response scores from the Blankenship Attitude Inventory. A multiple choice test, with KR = 0.79, was used to measure achievement. Statistical analyses included means, standard deviations, one-, two-, and three-way analyses of variance and t-tests. Considerable significant differences were found in school type, with achievement in agricultural schools much lower. Males outscored females in total results. Substantial and significant differences, all in favor of the BSCS students, were identified. (EB)