This study is concerned with teacher knowledge of learners' help-seeking behaviour. Teacher estimates of expected help-seeking behaviours of learners were compared with actual help-seeking of the learners. An in-depth study was deployed with one mathematics teacher and her grade 8 class of 20 learners solving mathematical word problems. Data were collected using a single-case design with semi-structured interviews, questionnaires and observations before, during and after two lessons. The help-seeking behaviour was conceptualised and analysed using 11 dimensions (clustered into 4 aspects) as used in the work by Gurtner. The four aspects include: intention to seek help; source of help (teacher vs classmate); type of help (hints and/or self-regulatory content knowledge) and reasons for help-seeking avoidance. The analyses indicate that the teacher had detailed knowledge of her learners' intended help-seeking behaviour. In many instances this teacher's knowledge of the source of help was congruent with learners' actual help-seeking. The congruency was taken to indicate how accurate knowledge on the part of the teacher can aid interaction and learning support. The teacher data provided evidence to expand Gurtner's 11 dimensions to 13, providing two additional reasons for help-seeking avoidance by the learners. These are termed 'uncaring' (referring to lack of engagement on the part of the learners) and 'ignorance' (referring to a lack of meta-cognitive awareness that help is needed).