Quality of students’ explanations in describing multiplication algorithms: the case of Napier bones.

We describe a didactic cycle involving the Napier bones algorithm, included in a wider research whose aim is to investigate whether and how the use of different kinds of artifacts can affect students’ explanations, supporting the understanding of some aspects of the multiplication. We present and discuss some data regarding group and individual tasks that allowed us to investigate how students’ explanations were and what semiotic representations they chose when using Napier bones.