We often assume that a high level of expertise in a topic is needed in order to be able to teach it. This is usually wrong.
Experts have built up a complex network of knowledge and skill – to the extent that they are no longer able to imagine what it’s like not even to understand the basics.
Experts have moved far beyond step-by-step sets of actions or thoughts and think about topics in more abstract terms. They therefore tend to teach those abstracted concepts – and those make no sense to a novice who hasn’t worked up through a series of scaffolded steps based on concrete actions and examples.
Experts have more complex and nuanced vocabulary to describe concepts. They are often unaware that they are describing things in language that appears opaque and jargon-filled to the novice.
Being an expert in a topic doesn’t mean you know how people can best learn it. For example, it might seem intuitive to an expert to simply explain the topic at length and in detail. But even a basic understanding of learning design tell us that this ‘passive learning’ approach won’t work.
Survivorship bias means that people who have been successful in developing expertise assume that their approach is what would work for novices, too
This is not to say that experts can’t teach. It’s just that teaching requires an understanding of how effective learning and teaching work combined with enough subject knowledge.
Research backing for this comes from the ‘earned dogmatism hypothesis‘.