The other day I had an interesting (but brief exchange) with Kelvin Bentley on twitter about MOOC completion.  This isn't really a topic that I come back to often, given that completion-rates for MOOCs, as a topic, seems to have kind of died down, but it is fun to come back to it. To my knowledge, no one has come up with some sort of taxonomy of the different degrees of completion of a MOOC†. But