Based on fieldwork conducted in two day care centres in Denmark, this paper explores knowledge and action as relational and intertwined phenomena in nursery teaching. Engaging with perspectives from actor network theory, emphasis is put on the socio-material distribution of knowing and acting. That is, how the nursery teacher becomes part of knowledge and action through an assemblage of various elements, such as packed lunches, children, noises, crumbs, another nursery teacher and a bucket. A notion of the sign is developed in which signs can be gestures, words or artefacts stabilised in a web of relations, hereby signalling the kinds of relations that are important to attend to. 'Signing in' is a way of becoming part of these relations. Against this background, this paper critically addresses ambitions to professionalise the field of early childhood education and care, questioning the divide between knowledge and action on which such initiatives are based.