Curriculum integration from a STEAM transdisciplinary perspective represents a profound challenge. This study delves into a transdisciplinary approach to primary education and the role of the arts through two STEAM projects in a programme for gifted students in Madrid (Spain). Participants include 111 students from eight groups (11-12 years old), five teachers and four external professionals. The teachers fulfill the dual role of both teacher and researcher, using participant and non-participant observation, video recordings, interviews and classroom journals and questionnaires. All the findings have been triangulated and coded by means of Activity Theory, using Atlas.ti8 software and statistical analysis. The results show the significance of learning and the creation of meaningful experiences as being related to a high degree of motivation and satisfaction, and to the integration of diverse areas in a participatory process in which the arts play a disciplinary and integrating role. A transdisciplinary STEAM approach is presented that could be paradigmatic for the field of primary education. [Translation from Spanish by Jennifer Martin.]