Teaching energy concepts by working on themes of cultural and environmental value

A considerable amount of educational research has been devoted to the teaching and learning of energy concepts and phenomena. Many studies have pointed out students’ common conceptions that can hinder their understanding and create typical learning difficulties. A number of teaching approaches have been proposed and tested: we consider, in particular, the gradual, the holistic, the historical, and the STSE (Science Technology Society Environment) approaches. Research results together with the work we carried out in teacher preparation and with in-service teachers led us to the conviction that it is necessary to overcome a too de-contextualized and technical approach to physics teaching. In particular, as far as energy issues are concerned, it is necessary to immerse physics contents into the context of scientific culture by discussing different interpretations and conceptions which caused historical debates, sometimes not completely resolved. This means to integrate the STSE approach with the historical one, and to take into account the conceptual and procedural dimensions of science learning. At this aim we propose to select specific driving issues which can promote the progressive construction of physics concepts and models while highlighting their scope and value and the connection to students’ cultural context. As an example, we present a teaching learning path, devoted to high school students, that has been developed around the specific problem of understanding the physical basis of the radiative greenhouse effect and global warming. We wanted to connect strictly the environmental aspects and the scientific content, and we paid particular attention to the conceptual progression and connections between different physics areas: understanding energy conservation principle requires differentiating the concepts of work, heat, internal energy, temperature, and, especially for the greenhouse effect, differentiating heat and radiation as means of energy transfer. The historical development of the idea of radiant heat shows how this process of differentiation was a long one. Our approach requires interaction between outdoor experimental activities, reflection in the classroom, and experimental work in the laboratory. Based on preliminary research with small groups of students we have pointed out a sequence of six cognitive steps toward the construction of a coherent explanation of the greenhouse effect. The teaching path was experimented in six high school classes, four with 17-18 years old and two with 15-16 years old students, for a total of 121 students. The results confirm the importance of passing through all the six considered cognitive steps: the greenhouse effect is a complex phenomenon and needs a progressive rapprochement. The analysis of the pre- and post- tests has shown clearly an increase in the consideration of the role of radiation in thermal processes, the awareness of energy balance in stationary situations, and a more correct and complex explanation of the greenhouse effect, even if some obstacles persist which will be challenged in a new cycle of refinement and implementation. The introductory and final discussions of the Earth Global Warming were effective to motivate students, who felt to be more engaged because of the general value and interest of the topic