We present the design and implementation of a teaching-learning sequence (TLS) on astronomy in a fifth-grade classroom. The specific topics were the local horizon and the path of the Sun in the sky. A key element of the TLS was the direct contact with the sky, realized through repeated observations of the local horizon and of the position of the Sun during the day, the use of instruments and three-dimensional models, and the integration of formal and non-formal learning environments (Museum of Natural History and Archaeology). The study was conducted following an empirical research design, aimed at investigating the process of conceptual change. The methodological approach was a student-centred, active laboratory approach, in which children were the protagonists of their learning. The evaluation of the TLS considered both the cognitive and the affective dimension of learning. To this end, a pre/post-test assessment was combined with a questionnaire administered at the end of the intervention. The results show evidence of conceptual change in all the children and high levels of engagement during the whole TLS, both at School and at the Museum.