Using anchoring conceptions for teaching statics of fluids

This research includes an analysis of previous research on the subject, a study of students’ conceptions (through questionnaires and interviews, about 200 students in all), the elaboration and experimentation of a teaching sequence. The school level targets are high school and first-year university students. We found that there is an important difficulty concerning the coordination between global and local descriptions of the physical situations, between the intuitive images of the fluids and the mathematical simplified models used in teaching. There is a difficulty in correctly linking Archimedes’ effect to the forces of pressure in fluids. As for teaching, our hypothesis is that students’ conceptions need not always be erased, but can also constitute useful "anchoring conceptions" to build a more complex conceptual structure. A short teaching sequence concerning pressure in the static of liquids has been elaborated. It makes use of an intuitive and qualitative model of liquids through an analogy with a set of sponge balls.