Mathematics teachers' perceptions about the end-of-secondary school external assessment in two educational contexts: implications for teaching and learning

End-of-secondary-school external examinations play a critical role in shaping teaching and learning, yet little is known about how teachers interpret their design and educational consequences across different systems. In this comparative study, we investigated through semi-structured interviews mathematics teachers' (n = 12) perceptions of the design of end-of-secondary school external assessment and its implications for the teaching and learning of mathematics in the Turkish Ministry of National Education Program (MoNEP) and the International Baccalaureate Diploma Programme (IBDP). Findings of the thematic analysis revealed clear contrasts. While the IBDP's criterion-referenced assessment was seen as aligned with curricular aims and fostering inquiry and conceptual learning, the norm-referenced university entrance exam (YKS) in MoNEP was viewed as misaligned with curricular goals and pushing teaching towards memorisation and test-taking strategies. Across both systems, teachers highlighted strong backwash effects, illustrating how assessment design impacts instructional practices and learning outcomes. The study suggests that aligning curriculum and assessment more closely, diversifying assessment formats and investing in sustained professional development are essential for fairer and deeper mathematics learning.