1. Institute of MathematicsFaculty of Teacher Education and Sports, Sogn og Fjordane University College, Sogndal, Norway. Email: frode.olav.haara@hisf.no
2. Institute of PedagogyFaculty of Teacher Education and Sports, Sogn og Fjordane University College, Sogndal, Norway. Email: eirik.jenssen@hisf.no; ingrid.fossoy@hisf.no; inger.karin.roe.odegard@hisf.no