International colloquium "mathematics education from early childhood to adulthood" location:Mons date:7 July 2005
Symmetry is one of the central ideas of geometry and plays an important role in other branches of mathematics, in science and in art. In this article, a path will be outlined starting from the simple idea “the two parts are the same” and finally leading towards symmetry groups and their subgroups. We will discuss some stages and pupil activities along this path. We will focus on some activities for 17-18 year old students during which they discover the utility of reasoning in terms of (sub)groups of isometries.