The teaching reform of industrial engineering sciences obliges teachers from various specialties to teach the “Enseignement Technologique Transversal” (ETT) subject. Since this reform, Industrial Science teachers have been teaching within the framework of ETT which is common to all specialties. The purpose of this article is to establish plausible links between teachers’ specialisations but also the way they design the energy chain within the framework of the ETT. Twenty-five teachers from different specialties (“Energy and Environment” [EE], “Mechanical Engineering” [ME] and “Information and Digital Technologies” [IDT]) responded to a questionnaire about energy. Six of them were interviewed individually and asked to model an energy chain and give their definition of energy. The results show that IDT teachers report a higher level of difficulty in teaching this energy modelling than ME and EE teachers. The case study suggests that ME teachers tend to define energy by the type of energy studied (mechanical, fluidic, renewable). IDT teachers define energy by its relationship to the physical concept of power. They also link the energy chain to the information chain. EE teachers tend to start the energy chain with a reservoir. They use the “W” symbol for the concept of work and define energy by its effects. The data collected establishes plausible connections between the teachers' specialisations and their way of defining energy and the functional model. This data analysis also reflects the curricular foundation of the functional model.