There have been times when we sit through a long lecture , the speaker a well known or established person in the field of topic, not a single point gets through even after it ended.
This reminds of a famous dialogue from 3 idiots where Rancho gives a demo lecture to the principal and when confronted by the principal it was engineering and not a philosophy class .He replies by saying that the principal is no doubt an expert at engineering , but was explaining how to teach to get across to students .
There was this special friend in every study group who taught better than the best knowledged teachers. Its this ability to connect and make it simple for others to understand that makes knowledge transfer successful. In short to be able to understand the listeners hold on subject and get it across in a manner easily understandable even in layman’s language is a skill different than having knowledge.
The ability to get across to students also requires special training but that is not enough due to all kinds of complexities involved the childs previous knowledge , his behaviour , attention span, exposure to ideas and topics outside school, family background on education etc .Hence outling , preparing and delivering a topic in a manner that can easily be grasped by children of that age is a challenge and requires much understanding from the childs point of view too. So if a child speaks of not having understood that’s being taught, it doesn’t mean the person teaching wasn’t Knowledgeable but just couldn’t get the topic across to him.