A systematic review of mathematical reasoning: process, product, or anything between?

Mathematical reasoning has long been emphasised as a central component of mathematics education and research. Nevertheless, few studies have synthesised how this concept has been treated both theoretically and methodologically in previous research. Reviewing the status of this treatment is crucial for understanding how the concept can be operationalised in classroom contexts. This review synthesises empirical studies on mathematical reasoning, addressing the question: How can mathematical reasoning in lower secondary education be understood through a synthesis of empirical evidence? Data were retrieved from seven databases, resulting in a full-text review of 57 articles. The analysis identified three different approaches to conceptualising mathematical reasoning as a theoretical construct: as a process, a product, or an ability. The review further provides an overview of the geographical and historical distribution of these approaches between 2003 and 2022. An important finding is that only a limited number of studies provide explicit definitions of mathematical reasoning. Furthermore, the results indicate a frequent disconnect between the theoretical treatment of the concept and its methodological operationalisation in empirical research.