ABSTRACT
INTRODUCTION AND OVERVIEW Mathematics seems to differ from physics in the role that common sense can play in its development. In physics, all great discoveries are related to great names, right from its beginning-Aristotle, Galileo and so on. In contrast, elementary mathematics was created by many unnamed people in many different places in the world and local communities still have their own informal mathematics related to their everyday and professional lives (for example, see Nunes, 1988). Recognising this role of common sense in the development of elementary mathematics, Freudenthal in his final work (1991) argued that, provided common sense is not blocked, attaining mathematical insights a bit more advanced than the most elementary ones is a question of extending one’s common sense and using it. H e often stressed the need to keep open the common sense sources of insight for learning. This is the perspective that will be pursued in this chap terwithrespectto fractions.
