I have seen many posts on the “so and so numbers of things that instructional designers or elearning professionals must do”, and many include the “chunking of information”. But what do they really mean by that? Displaying on the course lesson page a maximum number of words out of the total? Displaying a whole section? Making short videos? Short audio bites? Or just as many word as you can pack on the page? It can get confusing (at least to me) as to what really chunking means.
It has been proven for a long time that we can retain in working memory a number of “items”, which really mean concepts. In order to learn a new concept, it is important to first see the big picture of what we are learning (top-down), and not to worry about the details at that point. Then we can learn the interconnected concepts (the chunks) that serve as the foundation for what we want to learn so that, at the end of our study session, we are able to put the pieces together for the big-picture chunk of information (bottom-up). The point where these small chunks meet with the big picture idea is called the context where we are learning. Every time we need to remember that particular concept, we will recall this whole chunk of information, including the details, so that we would not have to use rote memory to remember all this information.
In terms of content for elearning, the above explanation applies to both text and media. A long video erodes attention the same way a long page with text does. We can only concentrate (focus our attention) for a few number of minutes (it varies but it could be between 15 - 25 min), then it becomes difficult to maintain concentration on the content. And this is the way I conduct my course design: presenting one idea as a chunk belonging to a bigger picture in the form of one lesson, section, page or whatever you want to call it, then as the learner move across the course where more chunks are being covered, this learner will arrive to the point where the context is presented and the learning of this new concept then takes place.
My favorite example is an online class in statics (because I am an engineer) where you want to cover the big picture subject of static equilibrium. Of course, the large picture is statics, the mechanics of bodies at rest or in constant velocity, but the subject of interest is static equilibrium. Within this subject you need to cover the static equilibrium of particles, then of rigid bodies, and within these two subjects there are a multitude of other subjects that need to be covered in order to understand how to analyze bodies in static equilibrium. The course must provide the context where all these chunks meet so that the learner can understand when to analyze a body as a rigid body or as a particle, when to use a vector approach or when to use a graphical approach to solve for forces acting on a body, and son.
The important point is this: don’t present your learners with two different concepts that they need to understand, present those concepts gradually so that they can master one before moving on to the next one. Also, I would recommend immediate assessment after they have covered the subject so that reinforcement occurs, and add a walk-through example so that they can understand how this concept is applied. In order to provide this context, another walk-through example (or case scenario) can be pertinent and a little more assessment to finally reinforce the material learned.