This paper presents a case study of how a teacher and nine-year-old students deal with mathematics in a practical technology project. By analysing videotaped dialogues between teacher and a pair of students working on constructing a house model, we identify challenges of meaningful inclusion of mathematics in the project. The dialogues are analysed in terms of an analytical framework where four categories of interaction patterns are combined with two main paradigms of mathematics teaching: the exercise paradigm and landscapes of interaction. The project in itself has a potential for facilitating landscapes of investigation in mathematics teaching. However, we find that the teacher as well as students adheres to the exercise paradigm when mathematics is involved in the activity. Two illustrating episodes from the project are examined and presented in detail in this paper. The findings illustrate that the conceptions teachers and students hold of what mathematics teaching means can act as an obstacle in attempts to realize mathematics teaching in creative and meaningful contexts for young students. We suggest that making the various purposes of a project more explicit may help overcome this obstacle, and that the mathematics involved might be taught in separate sessions in order to form a constructive part of a cross-curricular project.