While laboratory instruction is a cornerstone of physics education, the impact of student behaviours in labs on retention, persistence in the field, and the formation of students' physics identity remains an open question. In this study, we performed in-lab observations of student actions over two semesters in two pedagogically different sections of the same introductory physics course. We used a cluster analysis to identify different categories of student behaviour and analyzed how they correlate with lab structure and gender. We find that, in lab structures which fostered collaborative group work and promoted decision making, there was a task division along gender lines with respect to laptop and equipment usage (and found no such divide among students in guided verification labs).