Practical work is often highlighted as having a potential for high quality learning, and as a key component of research-based teaching in higher education. While critics in science education have pointed to the lack of clarity about the conceptions and aims of practical work, few have pointed to the mechanisms of in- and exclusion involved in practical work. This paper examines the intersection of tacit knowledge with student identities, focusing on the spatial dimension of practical work in higher education. Comparing ethnographic studies of fieldwork in geology and lab-based teaching in the experimental sciences, the paper shows that the ways in which students and teachers are distributed in space manifest patterns of in- and exclusion. Combining theories of tacit knowledge with recent theorizing of space and exclusion in education, the paper discusses the consequences of such basic aspects as proximity to teachers and access to interaction for who benefits from practical work. The paper argues that a clearer conception of practical work requires attention to the spatial dimension and its implications for the educational opportunities of students to access and interact with teachers.