Pre-service Teachers’ Common Content Knowledge Regarding the Arithmetic Mean

The main goal of this study is to determine the common content knowledge of a group of pre-service primary teachers regarding the arithmetic mean. The cognitive configuration tool proposed by the Onto-semiotic Approach of Cognition and Mathematics Instruction shows that the arithmetic mean can have a variety of meanings, and the application of this tool here revealed significant difficulties related to the students’ understanding of this mathematical object and some of its properties. This article concludes with some educational implications for teacher training in the field of statistics.