Evidence of student thinking takes a variety of forms (e.g. verbal responses, gestures) and has varying degrees of visibility within classroom interactions. The purpose of this study was to characterise the nature of pre-service science teachers' (PSTs') noticing skills of different forms of evidence of student thinking using video-based interviews. In the interviews, the PSTs were asked to describe what they had noticed in the videos that captured different forms of evidence of student thinking and 'think on their feet' to propose the next instructional moves as if they were the teacher. The PSTs' comments on the videos were analysed qualitatively with respect to the forms of evidence they noticed and how they interpreted and responded to the evidence. Several findings regarding the nature of PSTs' noticing skills were uncovered. First, the PSTs readily identified non-verbal forms of evidence, such as voting and student actions. However, some forms of evidence that potentially reveal the content of student thought, such as student artefacts, questions and verbal explanations, were less visible to the PSTs. Second, the PSTs used the identified evidence to infer student engagement levels, attributes and understanding and were generally able to propose instructional responses based on the student thinking that they had identified. Third, the findings also suggest that when the PSTs paid attention to the details of the evidence, they were more likely to connect their instructional decisions to student understanding at a content-specific level. The implications for research on PSTs' noticing and initial education are discussed.