Helen,
MOOC is about self learning at own pace. Discussion forum adds to the effectiveness of learner experience. Learners get the opportunities to ask queries, raise questions, share their views and ideas through discussion forum. Particularly this LCM approach to MOOC enables the learners to use discussion forum through a focus question.
Discussion forum enables the learner to be active learner while watching videos, reading/viewing resources in a conventional MOOC. While in LCM way of MOOC, LxI are the pivotal aspect where the learners get actively involved to discuss and share ideas and views in a more specific manner through focus question.