Pre-service Secondary Mathematics Teachers' Specialized Knowledge. A Study of the Definitions of Quadrilaterals

This paper deals with the specialized knowledge of pre-service secondary Mathematics teachers from Peru, about the conceptualization of quadrilaterals, using the MTSK model. We focus on understanding what their knowledge is like when they define quadrilaterals in an open-response questionnaire, plan a lesson and execute it. The research is an instrumental case study belonging to a broader interpretative investigation. They propose descriptive and partitional definitions, without questioning the necessity and sufficiency of the properties that they include.