This paper focuses on students in need of special education in mathematics (SEM students) and highlights teachers’ and principals’ reflections upon these students’ construction of knowledge in relation to two educational settings: the regular teaching setting and the test setting. The findings indicate that SEM students’ knowledge is legitimized only when displayed. However, there appear to be differences according to the specific setting. Different settings imply different knowledge representations, norms, and practices that need to be taken into account when reflecting, planning, and carrying out teaching in mathematics in relation to SEM.