Transposition didactique et complexification conceptuelle : contribution à l’étude du cas de l’électron.
FRECHENGUES Pierre, 1999

Key-words : electron, history of sciences, epistemology, didactics, complexity.

This thesis focuses on the construction of the concept of electron by secondary school pupils and on the different steps of the didactic transposition: scientific knowledge, constructing knowledge by pupils, knowledge to teach, and taught knowledge.
A brief review of the emergence of the scientific concept of electron (developed in “additional information ”) is given. We tiy to interpret the electron properties and the story of their discovery using the model of complexity elaborated for sociology by E. MORIN and extended to the analysis of systems by J. -L.LEMOIGNE. Then, we show how the introduction of electron in curricula was delayed by inductivism and positivism; their influence can also be found in the recent transposition ofthis concept. Current curricula in electricity are analysed thanks to a typology which shows their evolution since 1902. Then, we try to know how secondary school teachers interpret these curricula.
Finally, by means of didactical engineering, we analyse the construction ofthe concept of electron while it is leamed by pupils, mainly at the time of the study of some typical situations concerning oxidation-reduction in grade il (5 weeks teaching with exercises and questionnaires) ; a study ofthe interaction ofthe electron with a magnetic field is also tackled.
Our basic hypothesis considers that knowledges related to the concept of electron are put together by blocks, which are activated by situations. We investigate particularly the conceptual bonds inside this network, the place and role of the attributes of the concept, the links with the concept of atom and intensity, the difficulties in the change from microscopic to macroscopic points of view and the importance of some interlinking situations. We also study the effects of a change in curriculum.
In conclusion, the use ofthe intelligibility ofthe complexity to interpret the learning of the concept of electron is suggested in the classroom.