In order to develop elementary school children's environmental citizenship, the 21st century teachers have to improve their own environmental literacy, and electronic sensors can have an important role in that improvement. The research presented in this paper describes an environmental education project that uses electronic sensors to support future teachers in thinking globally, while sensing and acting in their local environment. Future teachers used sound sensors, temperature sensors, as well as carbon dioxide sensors, together with smartphones, to explore natural and urban systems in order not only to characterize these systems, but also to: (1) understand ecosystems' services and interconnectedness; and (2) identify environmental problems; and plan related solutions in what concerns climatic comfort and air quality. The data acquired and produced in ecosystems' explorations were selected and are presented in this paper, as well as the related interpretations. The learning results are related to: (1) the local characterization of a natural ecosystem and of the teachers' education school campus; (2) the differences and relations between Lisbon urban systems and the neighboring natural ecosystems; and (3) the identification of interventions to improve environmental quality of the campus. This research contributed to validate the use of electronic sensors and smartphones as a useful strategy to produce environmental information about the explored ecosystems, to link local and global approaches in environmental education, as well as to support students' actions, planned to enhance the Campus environment. [For the complete proceedings, see ED579282.]