Schulz, A., & Walter, D..  (2019).  ?Practicing place value?: How children interpret and use virtual representations and features. In U. T.  Jankvist, van den Heuvel-Panhuizen, M., & Veldhuis, M. (Hrsg.), Proceedings of the Eleventh Congress of the European Society for Research in Mathematics Education  (S. 2941-2948). Utrecht, the Netherlands: Freudenthal Group & Freudenthal Institute, Utrecht University and ERME.