Abstract
The aim of this study is to investigate the conditions under which the chemical transformation concept is taught and learned. The chemical transformation is a central concept of the chemistry curriculum in French-speaking contexts (France and Western-Switzerland) and it can be a key to understand natural/technical phenomenon like the carbon cycle. Thus, this concept is needed to understand complex issues like global warming. The purpose of this work is to explore the potential of the carbon cycle for teaching an environmental issue through chemistry lessons at the lower secondary school (13- to 15-year-old students). This approach is called “codisciplinary”. In French-speaking countries, the curriculum is organised into school disciplines, taught during distinctive time slots by specialised teachers at secondary level. Such an organisation questions the teachability of topics such as environmental issues and sustainable development. The carbon cycle is a common model in biology and geology: its structure in circle allows connecting human activities and their environmental consequences. From a chemical point of view, each arrow on the cycle could be modelled as a chemical reaction (photosynthesis, respiration, combustion, etc.). From our perspective, the integration of the carbon cycle in chemistry teaching could create the conditions for a codisciplinary approach. We study teaching practices by a questionnaire survey and, then by classroom observations. Four chemistry teachers participated in the study (two in each French-speaking context: Montpellier area in France, Geneva District in Western-Switzerland). The data were collected for two consecutive years. The first year, we video-recorded the ordinary teaching practices. The second year we suggested to the teachers to integrate the carbon cycle into their teaching of the chemical reaction. The resulting teaching was also video-recorded. On the basis of our results, we build codisciplinarity indicators. In other words, how chemistry’s specific concepts chemical reaction and the principle of conservation of the matter — in relation to carbon cycle and greenhouse effect models deepen the understanding of global warming. Also, we discuss the effect on students’ learning. On the one hand, about chemistry concepts learning, on the other hand about understanding the Anthropocene.