Designing methematic modeling competencey assessment questions based on Thalès in triangels for 8th grade students

Abstract

The assessment of mathematical modeling competence is a crucial component of competency-based evaluation aligned with Vietnam’s 2018 General Education Program. However, designing tasks that effectively assess this competence at the lower secondary level remains challenging, particularly in geometry. This paper focuses on the topic of Thales' theorem in triangles (Grade 8) — a concept with strong visual and practical connections — to propose a design procedure for modeling-oriented assessment tasks. A sample task is developed to illustrate the process, including identifying learning goals, selecting mathematical models, building real-life contexts, and constructing appropriate questions. The study provides practical insights into competency-based assessment in mathematics education and may serve as a useful reference for teachers, pre-service teachers, and educational researchers.