Findings from our longitudinal study on spontaneous collocated MOOC study groups suggest that groups tend to stick to a certain kind of study style. A strong positive relationship was found between how often students pause and replay the videos and the synchronicity among groups. Further, synchronous groups tended to perceive better group learning experience, in terms of self-assessed quality and mutual participation. p. 1

Research has revealed that the more open an online course is, the more the learners seek to engage in groups as opposed to an open network (Mackness, Mak & Williams, 2010). p. 1

(1) What group learning styles emerge with spontaneous MOOC study groups? Do they watch lecture videos synchronously? (2) Do the study styles affect students’ perception of their group learning experience? p. 2

The two plots presented before visualized how group students interacted with videos and how synchronous and asynchronous group patterns look like. To quantify these patterns, we introduce linearity index and synchronicity index. p. 3

Less individual engagement in videos leads to higher synchronicity. This is simple to interpret, since fewer video interactions increase the chances for students to watch and digest the same topic at the same time, which offers a common ground for them to foster arguments and discussions. Linear watching does not always imply lack of independent thinking. Highly synchronous groups, according to our semi-structured interviews, reported that they usually noted down the problematic video moments while watching the videos, and brought out every question in the group discussion right after everyone finished watching. The groups were selfregulated, and students intentionally started and finished video watching more or less simultaneously. p. 6

Another important finding in our research is that groups may work with different styles, but they were shown to stick to the initial pattern. This is perhaps because a unique group atmosphere was formed for each group in the first time, and participants got used to it. The stability of such group patterns in terms of synchronicity has a big implication for organizing MOOC-based study groups. Though groups can be spontaneous, good practices (e.g. explicitly asking learners to stay synchronized) should be suggested to study groups, preferably before their first session. p. 6