There's nothing educational researchers love better than a good taxonomy, and so it's not surprising to see these authors draw from the literature to find this: "The energy and effort that students employ within their learning community, observable via any number of behavioural, cognitive or affective indicators across a continuum." There's a table of examples of each (for example, integrating ideas, sense of belonging, attention/focus). But the table leaves me wanting a principled distinction between these three elements, and suspecting there isn't one to be had. The paper then takes a hard right turn and introduces us to a "bioecological student engagement framework," which includes a microsystem, macrosystem, exosystem and exosystem. Then a sharp left, as we read about the influence on engagement created by the student, learning environment, teacher, curriculum, peers, family and outcomes. The overall model (illustrated) produced is essentially a mash-up of all of these factors. Taxonomies galore. But no sense of what the arrows in the model signify, and what underlying principles (if any) would be at work.