The topic of coupled oscillations is rich in physical content which is both interesting and complex. The study of the time evolution of coupled oscillator systems involves a mathematical formalization beyond the level of the upper secondary school student's competence. Here, we present an original approach, suitable even for secondary students, to investigate a coupled pendulum system through a series of carefully designed hands-on and minds-on modelling activities. We give a detailed description of these activities and of the strategy developed to promote both the understanding of this complex system and a sound epistemological framework. Students are actively engaged (1) in system exploration; (2) in simple model building and its implementation with an Excel spreadsheet; and (3) in comparing the measurements of the system behaviour with predictions from the model. (Contains 5 figures and 2 footnotes.)