The investigator taught all experimental classes during the 12 days of instruction, utilizing ten units of a locally-developed text, a test based on the materials, and a series of slides and related discussion. The experimental group included 97 subjects enrolled in three classes studying second-year biology and one class studying tenth-grade social studies; the control group included 108 students enrolled in five classes studying second-year biology. Three subscores (biological concepts, nature of the scientific enterprise and the work of scientists, and social implications of the concepts) and a total score were obtained from the 90-item multiple-choice test administered to experimental and control classes as both a pretest and a posttest. Significant achievement gain on the three subscores and the total score was found for all classes in the experimental group. The control group showed no significant gains. In responding to a student questionnaire, a majority of the students (73 percent) expressed a positive opinion about the interest potential of the reading material, and a majority (57 percent) also indicated that the reading material was less difficult than that ordinarily experienced in biology classes. It was concluded that the performance of the experimental classes met the criteria under which the socio-historical approach was to be judged acceptable. (Author/CP)