Academic learning experiences provided during a unit on genetics were examined in this case study report of two honors biology classes. It was conjectured that the nature of students' work and how it is handled by teachers affects how students attend, how they process information, what skills they practice, how they are evaluated and ultimately what they learn. Specific questions that were investigated include: (l) how did the teachers translate their knowledge of the content and curriculum into sets of learning tasks; (2) how were the tasks managed by teachers and accomplished by students; (3) what were the effects of the teachers' task decisions on the kinds of learning experiences students had with the content; and (4) what opportunities were available for learning genetics concepts. Classroom tasks and relationships between tasks and other aspects of instruction were analyzed and problem areas in task management were identified. The interviews, analyses of student performance on quizzes, and interactions during class provided evidence that there was poor student understanding of concepts and procedures in several specific areas. Findings further suggested that teachers need to make careful choices in planning classroom tasks and in maintaining a balance between curricular demands and classroom needs. Tables showing sequence of task content in the two classrooms and summarizing genetics unit tasks for each teacher are appended. (ML)