The Scottish mathematician John Napier is best known for inventing the logarithm. However, in his attempts to facilitate multiplication, he left behind something special: the so-called calculator rods. These sticks are based on an old calculation technique called gelosia. This technique can be taught …

In this episode, I describe some activities on the history of geometry. Geogebra is first used to visualize a primary source from Descartes, and then to create the conchoide of Nicomedes. In the last part the so-called human conchoid is described, a form of embodied cognition to let your students get …

In this episode two activities from the mathematics teacher training programme are described. Both of them are based on the so-called “expert-method” in Dutch terminology, or “jigsaw technique” in American educational literature. It relies on dependability between students. It breaks classes into groups …

The number we call π has a long and varied history. In this article we look at its early origins, using Egyptian, Babylonian and Greek sources from more than two thousand years ago. These sources offer wonderful opportunities to introduce meaning and value in a first grade class, even without the need …