Teaching and Learning Floating and Sinking: Didactic Transformation in a Density-Based Approach

This essay synthesizes more than a decade of research, most of which has been published, on the teaching and learning of floating and sinking (FS) phenomena. The research is comprised of the iterative design, development, implementation and evaluation of a Teaching-Learning sequence (TLS) for the teaching and learning of density within FS phenomena. It was initiated within the frame of the European Community supported "Materials Science" project. Due to the many, different aspects of the project, each publication has focused on a particular part of the study (e.g., effectiveness and the iteration process). The didactic transformation for the teaching of FS phenomena is presented and discussed here. In doing so, it is essential to mention: (a) the students' ideas as the main cause of the scientific knowledge transformation, (b) the scientific/reference knowledge, and (c) the knowledge to be taught and its limitations. Thus, we intend to describe and justify the didactic transformation process and briefly synthesize the published (from previous papers) and unpublished results to show its effectiveness.