The paper presents an experience carried on in the fifth class of a primary school in Italy (age 11), where the collective composition of a song was the way to develop abstraction, deduction and inference abilities, beside the transfer of specific knowledge and information about the management of urban waste. In order to educate the local community on waste management and reduction, within the framework of the Waste Reduction Plan (PRR) launched by the town of Caronno Pertusella (a town in Lombardy/Italy, not far from Milan), primary and intermediate schools were involved, through several activities on the subject. Among the different experiences, a fifth class of a primary school was involved in the composition of a song, as an experimental activity aimed to explore the potentiality of different ways of teaching and to enhance the pupils capability to learn. Children wrote the lyrics, as an usual homework composition, while they also learned how a rock& roll song is structured. This task required a long and complex (for the children) process of composition, selection, reduction, phrasing for matching metrics, and so on. The experience was completed with the performance of the children singing the song as a choir, with the recording in a studio of the composed song, and with the final production of a CD. Moreover, pupils created a choreography, set up by themselves, and made two live public performances. The paper describes the experience carried on by the children, the role played by the teachers, and the lessons learned in terms of problems solving, of abstraction and synthesis capabilities, and of a deep learning about waste management, self-discipline and team building.