Invited ignition talk at the Leibniz Research Alliance OpenScience research symposium “Open Practices IN Education (OPINE)”, November 14-15, 2019, Frankfurt/Main (Germany). Slides: Links: symposium abstracts available online on Zenodo extended bibliography, see the open library at Zotero Abstract An excellent candidate for sloganizing is the word ‘open’. Immediately one uses it, the options polarize. To be open … is to be not closed, restricted, prejudiced or clogged; but free, candid,...