This research highlights the difficulties faced by a student learning scientific knowledge in a society with an oral or poorly literate tradition. It shows the reasoning and the universe of reference on which a pupil in Africa relies to explain a scientific phenomenon, in a school situation of knowledge writing. It shows the relationship that can exist between the popular cultural context of orality and the writing of scientific school knowledge by pupils. Considering this dual relationship, she rejects deterministic and deficitarist conclusions, proposing a didactic approach to science that takes account of students' traditional culture. Such a didactic approach would enable pupils to appropriate scientific knowledge, and to exercise reasoning, critical thinking and reflective memory, thus promoting the transition from traditional to modern scientific knowledge.