Teachers require support in developing the pedagogical skill of interpreting students' mathematical thinking and providing effective feedback that promotes learning. However, there is a lack of research assessing the quality of feedback based on teacher noticing in mathematics classes. This study analysed 20 preservice teachers' (PSTs) feedback approaches through two perspectives: mathematical alignment and the responsiveness of feedback to students' mathematical approaches. The findings indicated alignment of the focused mathematical concepts/processes in noticing and feedback. PSTs paid more attention to mathematical accuracy than the strength or potential of students' strategies. Furthermore, there was a relationship between the complexity of student solutions and PSTs' depth of noticing and the cognitive demands of feedback.