How exactly and under which circumstances does the learning of the fundamentally new occur? To focus on this question, learning environments with core topics of mathematics and computer science are examined. In the focus of digitalization, computer science and its connection to mathematics will play an important role in future curricula, making it an interesting object of investigation. Furthermore, at primary level, computer science topics are about to be included in every subject, including mathematics. The paper presents an ongoing study that examines, how the topic of computer science connected to mathematics learning can be approached in primary schools and what and how meanings are negotiated. The focus will be on the question, what roles consensus and dissent play in interactional processes of negotiation and how the learning of the fundamentally (Miller, 1986) new occurs in collective argumentation between pupils.