Learning engagement can be measured by the quality of interaction that a learner has with his/her co-learners and the level of response to the instructor. Whether learning engagement is higher in the online environment or a classroom session, is a debatable topic. I think it depends upon the level of maturity of the audience and the type of topic under discussion. The manner in which the program is structured and the way in which the level of engagement is tested also plays an important role. The online program designed with intermittent quizzes, peer review or frequent tests can ensure more engagement, as opposed to the one that relies on summative assessment. Again, the extent to which the engagement is superficial or authentic is hard to determine.

My argument is that intrinsic motivation works best to ensure engagement among adults. After a person reaches a certain age and achieves considerable professional caliber, it becomes a lot more challenging for the course developers to motivate them to study. The adults typically juggle with their time and have a lot more to focus upon, compared to a full-time student. So the grades awarded or the accolades do not motivate them too much. The course designed for such individuals needs to be focussed more on catering to intrinsic motivation factors, rather than extrinsic ones. These factors can be the value, against the time invested, that they see themselves deriving from the course. The flexibility that the course structure offers to them and the level of interaction with co-learners, that it provides are also a deciding factor. Adults may find it more valuable to have a discussion forum, where learner with similar interest and the instructors can have an open discussion and talk about their experiences. This can be more enriching, rather than the one way, assignment-based, grades based teaching-learning which is more focussed on extrinsic motivations.

Hence, the idea here is that while structuring the course for adults, the instructors should bear in mind that the course outcome is targetting towards satisfying the intrinsic motivational factors, rather than on extrinsic ones.

The following links have been referred to, for the above writeup:

https://www.cael.org/alert-blog/differences-in-adult-learning-and-motivation

https://www.talentlms.com/ebook/learner-engagement/definition

https://www.efrontlearning.com/blog/2018/03/learner-engagement-strategies.html

Carey, Benedict (2014). How We Learn: The Surprising Truth About When, Where, and Why It Happens (Kindle edition).