In this case study, we explore students' communication during practical work in physics at an upper secondary school in Sweden from a sociocultural perspective. We investigate the relation between the interaction and content of students' communication and outcomes of their actions, with the purpose of finding new knowledge for informing teachers in their choice of instruction. We make discourse analysis of how students interact but also of what students are discussing in terms of underlying content at a linguistic and cognitive level. Twenty students divided into five groups were video recorded while performing four practical tasks at different stations during laboratory work about motion. An analytical framework was developed and applied for one group to three parts of the transcripts in which three different talk-types occurred. Discursive, content, action and purposive moves in the process were identified for each talk-type at both linguistic and cognitive levels. These moves represent information concerning what the teacher actually assigns students to do, and how students make meaning of the activities. Through these different communicative moves, students experience how laboratory work can enhance their competence to collaborate in a scientific environment with complex practical and theoretical questions to solve quickly. Implications of the findings are discussed.