Teacher feedback can be described as a complex interactional pattern between teacher and student. Formative outcomes of assessment are considered to be enhanced when students understand aims and criteria. In order to better understand the processes of teacher feedback and to improve teaching and classroom assessment, there is a need for research on students' perspectives on feedback. The present study aims to conceptualise how primary-school students construct meaning from teacher feedback. The study was based on focus group interviews with 23 students in grades 2 and 3 (7-9 years old). Constructivist grounded theory was used throughout the study. According to the findings, primary-school students conceptualise teacher feedback as communicating a lot of "musts", centred on learning, involving what the students perceived as things they must learn and what they must do in order to learn. These musts concerned both academic learning and behavioural issues, including tensions between different musts.