Synchronous computer-mediated communication is often used as a means to achieve activelearning through collaboration. This paper is based on an ethnographic case study ofsynchronous communication. The synchronous communication is carried out between students in lower secondary school collaborating in a cross-border project involving the native language subjects Danish, Norwegian and Swedish. The project is aimed at promoting the students` Scandinavian inter-comprehension skills. The objective is for the students to use their own native languages in their communication whilst trying to understand the neighbouring languages used by their interlocutors. The aim of this paper is to analyse the students` use of situated semiotic structures in order to solve comprehension difficulties as well as emergent technical problems. In the emergent situations where the students face technical or language-based problems they use an interplay of different semiotic structures. They creatively and spontaneously use oral and written communication in different ways by using smileys, colours, gestures, grimaces, talking slowly and by sending smartphone pictures. Furthermore, they make use of different conversational forms such as online chats, Google Translate, and webcams. Synchronous communication is vulnerable because of the dependency relationship arising between the connected classrooms in different schools and countries. The multiple forms of conversation are dependent on the emergent situation and are dominated by the written mode.