There is a call for more interactive and student-centred pedagogy in higher education. This also concerns physics laboratory work, where student investigations are too often passive repetitions of close-ended tasks with little guidance from teaching assistants. To address this gap, a laboratory course was designed to enhance active student participation and interaction between students and teaching assistants. A seminal part of the course was the whole-class teaching sessions within which students had the opportunity to reflect on and orientate towards experimental work. Whole-class teaching sessions of four physics laboratory teaching assistants were carefully explored to determine how student-centredness was apparent during these sessions. Particular attention was given to the interactions and communication between teacher assistants and students. The results revealed different ways in which student-centredness can be facilitated in physics laboratory settings through communication, including dialogic elements. These elements consisted of eliciting students' ideas and explicitly linking their experiences to the discussions. Teacher assistants with a pedagogical background implemented dialogic communicative approaches when orchestrating instructional dialogue and linking different activities. Implications for teacher assistant training are discussed.