This study investigated the implementation of a 7th grade biology curriculum ("Animal and its Environment") in Israel. The curriculum has seven parts, each one with a dictated sequence including well-defined objectives, suitable activities, and assigned materials, with little degree of freedom for the teacher. A primary concern for the study was to identify reasons for dissatisfaction which has accompanied new science curricula implementation. The sample included 42 junior high school teachers in 28 schools spread throughout the central area of Israel, and included urban, rural, and kibbutz schools. Discrepancies between original curriculum intentions and their translation to formal materials, and discrepancies between developed learning activities and their operation in the classroom were examined, focusing on sub-variables related to the objectives, materials, activities, and strategies between ideal (philosophical directions) and formal (translation of ideal into tangible materials) levels. Results are reported for non-traditional sub-variables implemented completely, traditional variables implemented fully, and non-traditional sub-variables implemented in ways which were not in accordance with the aims of the curriculum developers. Although some objectives were implemented (including those related to subject matter and integrating laboratory work into regular class sessions), others (mainly those related to affective domain and higher order inquiry) were partially/totally lacking. (JN)