Enseignement/apprentissage des sciences physiques : construction du concept de période du courant alternatif à partir d’un oscillogramme par la NOS comme mode de transposition didactique

Abstract

Many secondary school students in Cameroon face significant difficulties in determining the period of an alternating current (AC) from an oscillogram—an essential element in understanding periodic phenomena in electricity. This study aims to explore the didactic conditions conducive to building this concept, drawing on the principles of the Nature of Science (NoS) as a framework for didactic transposition. Grounded in a theoretical approach that combines the principles of NoS, socioconstructivism, and Peirce’s semiotic theory, the study adopts a mixed-method quasi-experimental methodology. Quantitative and qualitative data were collected through a diagnostic questionnaire and student work, within a third-year class at Collège Saint Bruno de Logbikoy. The designed didactic sequence consists of seven progressive activities: qualitative construction, unit conversion, reading coordinates and physical quantities, mathematical formalization, articulation between intuitive and formal approaches, and summative assessment. The results show that manual tracing and active, comparative observation of oscillograms promote active and structured conceptualization of the period. The explicit integration of NoS helps to overcome common learning obstacles, such as confusion between period and half-period or difficulty linking graphical reading with mathematical expression. This research demonstrates that a NoS-based approach serves as an effective lever for enhancing students’ understanding of complex physical quantities by integrating observation, sensory experience, and scientific formalism. It opens promising perspectives for a contextualized didactic approach that embeds the history and epistemology of science into teaching practices.