Published on in Vol 8, No 3 (2020): Jul-Sep
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/19037, first published
.
1 Multimedia Communications Lab, Technical University of Darmstadt, Darmstadt, Germany
2 Institute of Sport Science, Technical University of Darmstadt, Darmstadt, Germany
3 Research Group Didactics of Mathematics, Technical University of Darmstadt, Darmstadt, Germany