This paper reports a predominantly qualitative classroom study on cooperative learning about nature of science (NOS) using a case from the history of science. The purpose of the research was to gain insight into how students worked with the historical case study during cooperative group work, how students and teachers assessed the teaching unit, and in what ways students' ideas about selected aspects of NOS changed as a result of the teaching unit. In cooperation with two biology teachers, a four-lesson teaching unit about NOS and the early research on Archaeopteryx was developed, field-tested, modified, and tested again. Altogether, five classes of 10th and 11th grade students from two Swiss schools participated. Data were collected by videotaping group work, interviews with student groups and teachers, questionnaires, and pre- and post-tests about NOS conceptions. Results show that group work was mostly of good quality, both with regard to students' cooperation and understanding of the case study. Second, both the topic and the instructional design of the unit were judged very positively. Third, students showed more informed views on the selected target NOS aspects after the teaching unit. The paper ends with conclusions regarding teaching and learning about NOS, cooperative learning and questions for future research.