The diagram at the beginning of the "Dynamic Forms of Communication" section is exceedingly poorly designed. As best as I can tell, it's supposed to be a digraph where the nodes are the students, the instructor, and the content; and the edges are communication channels.
The problem is, instead of having edges going from student to content and teacher to content, they added another node labelled "both" and put edges pointing from that node to content. In a graph with only three nodes and no multiple edges, there's no excuse for introducing a "both" node. The diagram would have been much simpler if it had been laid out as a triangle, with edges connecting the student node and the teacher node to the content node and no "both" node whatsoever.
The only reason I can fathom for laying out the diagram like this is because this way, all the nodes are colinear and none of the edges are curved, making the diagram look like a line segment. This would then reinforce the idea that the model of learning is "linear". There are many things I could say about this, but really, if you're so bad at abstraction that you need a diagram to be a straight line to call it linear, you probably shouldn't be teaching in the first place.