The development of creative processes within the framework of music and dance constitutes an opportunity to promote and integrate learning from different subject areas. In these activities, the moments of knowledge transfer between the different parts of the curriculum emerge as key moments in the process. This article identifies and analyses the critical events that arise when carrying out group work based on the integrated learning of music, dance and mathematics around the concept of symmetry. For this purpose, and within an action-research framework, a 20-hour didactic sequence was designed and implemented, which focused on the creative processes followed with students in the last year of primary school (11–12 years old) at a center near Barcelona. The data obtained through classroom observations and semi-structured interviews with the students brought to light the critical events that occurred in this creative, interdisciplinary context. The results show that the use of different forms of expression and the changes that students introduce when using one or another language to express their own ideas or knowledge are key moments in the advancement of joint creative activities and also of learning in itself.