This article presents first results of an ethnographic research project in a Luxembourgish primary school that accompanied the development of a school project by children from the fifth grade. Analysing the data children themselves collected with Kodak Zi8 cameras in order to document their project activities, it investigates their possibilities and constraints to become designers of a "third space" within the educational institution. The author draws on Emile Durkheim's educational sociology in order to simultaneously analyse the educational processes of socialisation and subjectification that occur when children are legitimated to take part in the design of their own learning processes within school. The analysis focuses on the social languages children are drawing on and creating when shaping their school project in and through the collected data. It succeeds in depicting the interplay of structure and agency in children's practices and in demonstrating children's capability to contribute to their subjectification as social beings and to co-design the educational institution they are socialised by. However, it also points to the institution's mistrust and constant endangering of children's initiative and constitution as social actors. In this sense, the article deals with the possibilities of and obstacles to transformation of institutions of learning from within and bottom up. (Contains 9 notes.)