A classroom-based dataset on phase-level assessment of mathematical modelling processes in upper secondary education

This dataset documents upper secondary students’ engagement with mathematical modelling through phase-level assessment. It contains anonymised CSV files reporting phase-level scores based on a five-phase modelling framework (understanding and structuring, mathematisation, mathematical resolution, interpretation, and validation), together with a detailed codebook and comprehensive instrument documentation. Data were collected in an authentic classroom context using curriculum-based modelling tasks and a structured data collection grid aligned with a unified phase-based scoring rubric (0–1–2). Phase-level scores were first attributed manually on the basis of students’ written productions and subsequently recorded through automated digital entry. The dataset is provided in reusable, non-proprietary formats to support transparency and reuse in research on mathematical modelling processes, assessment methodologies, teacher education, and the development of learning analytics or AI-supported educational tools.