Explaining skills are among the most important skills educators possess. Those skills have also been
researched in recent years. During the same period, another medium has additionally emerged and
become a popular source of information for learners: online explanatory videos, chiefly from the
online video sharing website YouTube. Their content and explaining quality remain to this day mostly
unmonitored, as well is their educational impact in formal contexts such as schools or universities.
In this study, a framework for explaining quality, which has emerged from surveying explaining
skills in expert-novice face-to-face dialogues, was used to explore the explaining quality of such
videos (36 YouTube explanatory videos on Kepler’s laws and 15 videos on Newton’s third law). The
framework consists of 45 categories derived from physics education research that deal with
explanation techniques. YouTube provides its own ‘quality measures’ based on surface features
including ‘likes’, vi…