The case of the Case of Benny: Elucidating the influence of a landmark study in mathematics education

• We report the most common purposes for citing Erlwanger's (1973) Case of Benny.
• The case is most frequently cited to support the claim that students have idiosyncratic conceptions of mathematics.
• A common purpose for citing the case is to support the claim that correct answers to not imply correct understanding.
• The case is viewed by many as exemplary qualitative (case study) research.
• The case is used to support the claim that there are serious difficulties with behaviorist-based learning systems.

Stanley Erlwanger's Case of Benny is seen by many as particularly influential in the mathematics education research community. This paper reports the results of a study designed to describe the nature of that influence. Through an analysis of academic references to the Case of Benny from the past 40 years, five primary purposes for citing the case were identified. These purposes revolve around the themes of student mathematical conceptions, the relationship between correct answers and understanding, the value of qualitative research, the impact of a behaviorist-based curriculum, and students as sense makers. The paper concludes by using these themes to reflect on the past 40 years and to look ahead to the future of research in mathematics education.