INVESTIGATING STUDENTS ’ UNDERSTANDING OF LOCUS WITH DYNAMIC GEOMETRY

Dynamic Geometry (DG) offers new possibilities for the investigation of loci. The two functions "Locus " and "Trace " provide complementary tools for thinking about loci: "global " in the Euclidean sense, "local " in the pointwise sense of analytic geometry. By using Trace the concept of functional relationship can be explored, an idea which is neglected in the current curriculum. We report on a small experiment with 15 year old students, in which we compared the students ' understandings of the 'local ' and 'global ' structure of loci under the different cognitive and cultural influences of working with conventional tools (compass and straight-edge) or DG