The ability to communicate is a separate skill from the ability to comprehend something. Once you separate the two skills you get 4 classes of people (with gra

The ability to communicate is a separate skill from the ability to comprehend something. Once you separate the two skills you get 4 classes of people (with gradations): 1. don't understand it, cannot explain it. 2. do understand it, cannot explain it well. 3. don't understand it well, can explain it well. 4. understand it well, explain it well. Number 2 are good practitioners and not as good teachers. Number 3 are good teachers but not as good practitioners. Number 4 are good teachers and good practitioners. Everyone wants to learn from a number 4, but they are more rare then the 3s and 2s. Between a 2 and a 3, you'd rather learn from a 3. If you don't need to learn, you'd probably rather work with a 2 than a 3. Basically, even if their mental model isn't perfect, they deliver explanations that can quickly lead others to at least be as good as them and possibly better quickly if you can see the mistakes in their mental models (their descriptions could potentially be 100% accurate without it reflecting their poor mental model). Anyways, this observation leads to the standard cliche, "Those that can, do; those that cannot, teach."