How can half of a half become a third?

In the next episode of Spøkelser etter avdøde størrelser (Ghosts of departed quantities), there will be a semi-structural conversation between Niclas Larson and Zelha Tunç Pekkan about a research report Zelha got accepted for the PME 49 conference in Helsinki this summer. The study is based on pre-service and in-service teachers watching video clips with pupils working with fractions. Zelha will also present the working group she will organise at the same conference. The episode will be published on Thursday.