1. Institute of Physics and Astronomy, ELTE Eötvös Loránd University, Budapest, HUNGARY
2. Czuczor Gergely Benedictine Secondary School, Győr, HUNGARY
3. Physics Education Research Unit, University of Udine, Udine, ITALY
4. Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, GERMANY