How do preservice mathematics teachers select and transform mathematical problems into real-life contexts?

This study investigates how preservice mathematics teachers select and adapt textbook problems into real-life contexts through a realistic transformation procedure. The study involved 49 final-year preservice mathematics teachers (35 males, 14 females) enrolled at a state university in northern Turkey. Adopting a qualitative case study design, we analyzed 98 textbook problems selected and transformed by participants and drew on two rounds of semi-structured interviews to examine their decision-making during problem selection and transformation. Participants’ task-design approaches were categorized based on their worksheets, transformed tasks, and interview accounts into two approach types: creating (re-contextualizing the task by constructing a new context) and elaborating (retaining the core mathematical structure while enriching an existing context). Because the study required task modification, an adhering approach (treating the textbook as an authoritative script and implementing tasks with minimal or no modification) was not used. Results show that both approaches improved the realism of problems, with particularly strong gains in contextual proficiency. Across both approaches, participants frequently incorporated realistic data and dialogue. Affective proficiency also improved but remained more challenging to establish at a fully sufficient level. The findings provide implications for teacher education on supporting preservice teachers in designing contextually plausible and purpose-driven mathematical tasks.