What makes an expert teacher?

What can we learn from experts on expertise? Some notes from this classic book from Chi, Glaser and Farr

1. Experts Excel Mainly in Their Own Domains.

"There is little evidence that a person highly skilled in one domain can transfer the skill to another."

This point is possibly the central one in the book and one which most people struggle with. Being an excellent teacher in one subject doesn't mean you can teach any subject. In fact even within one subject area there is not a lot of transfer: an expert secondary school English teacher would be useless at teaching 5 year olds how to read. Likewise, teaching students a set of generic skills is unlikely to lead to them becoming proficient in other areas. You can think deeply about something you know a lot about - generalised 'thinking skills' doesn't come into it.

"The obvious reason for the excellence of experts is that they have a good deal of domain knowledge. This is easily demonstrated; for example, in medical diagnosis, expert physicians have more differentiations of common diseases into disease variants (Johnson et al., 1981). Likewise, in examining taxi drivers’ knowledge of routes, Chase (1983) found that expert drivers can generate a far greater number of secondary routes (i.e., lesser known streets) than novice drivers."

2. Experts Perceive Large Meaningful Patterns in Their Domain.

Possibly the biggest difference between experts and novices is that they actually see problems differently. In education this is a crucial ability. Simply put, expert teachers have a superpower that novice teachers don't: they can see a whole range of things such as pre-empting misbehaviour before it happens to sensing whether a student is not understanding something. They will have a range of different ways of explaining the same thing in a way that meets the needs of all students. This comes not just from extensive experience but specific knowledge.

"It should be pointed out, however, that this ability to see meaningful patterns does not reflect a generally superior perceptual ability; rather, it reflects an organization of the knowledge base."

3. Experts are Fast; They Are Faster than Novices at Performing the Skills of Their Domain, and They Quickly Solve Problems with Little Error.

Experts know what to do when they don't know what to do. A great deal of expertise in teaching is about the automation of a range of strategies which can be recalled in an instant. This not just a feature of instruction, an expert teacher can see patterns in a class set of books that a novice can't and will know exactly what to do next lesson as a result of what they see. Most of this expertise comes from the fact that they don't have to think about it.

"A further possible explanation for experts’ speed in solving problems rests on the idea emphasized earlier that experts can often arrive at a solution without conducting extensive search."

4. Experts Have Superior Short-Term and Long-Term Memory.

This point is a little deceptive. It's not that experts have a better working memory, it's that they have more stuff in their long term memory. In other words, they just know more. This is also a key claim from cognitive load theory.

"With recently presented materials, experts’ recall seems to exceed the limits of short-term memory. This is not because their short-term memory is larger than other humans’, but because the automaticity of many portions of their skills frees up resources for greater storage. Experts seem to excel in long-term recall as well."

5. Experts See and Represent a Problem in Their Domain at a Deeper Level

Similar to point 2, novices tend to see problems in a superficial way but don't actually realise it. It takes expertise to know what you don't know.

"An easy and robust way to demonstrate this is to ask experts and novices to sort problems and analyze the nature of their groupings. Using physics problems, Chi, Feltovich, and Glaser (1981) found that experts used principles of mechanics to organize categories, whereas novices built their problem categories around literal objects stated in the problem description."

6. Experts Spend a Great Deal of Time Analyzing a Problem Qualitatively

This is a development of the idea that experts see things differently and probably the best evidence for rejecting the idea that we should teach kids to 'think like a scientist' - you can't think like a scientist if you don't have the knowledge of a scientist.

"What do the experts do when they qualitatively analyze a problem? Basically they build a mental representation from which they can infer relations that can define the situation, and they add constraints to the problem. Paige and Simon’s (1966) well-known example illustrates this by asking students to solve simple algebra word problems, such as: A board was sawed into two pieces. One piece was two thirds as long as the whole board and was exceeded in length by the second piece by four feet. How long was the board before it was cut? Paige and Simon found that some students immediately applied equations, which then resulted in their coming up with a negative length; others, however, remarked that the problem was meaningless because one cannot have a board with a negative length. One can conclude that those students who paused had formed a mental model of the situation and made some inferences about the relation between the boards."

7. Experts Have Strong Self-Monitoring Skills

One of the paradoxes of metacognition/self-regulation is that teaching these skills explicitly doesn't always result in being better at these skills. Very often, experts with really strong metacognitive skills have such a deep understanding of a domain that the skills are a sort of by-product of the knowledge. In other words, an expert can have a very high level of metacognition without ever having heard of metacognition.

"Experts’ self-knowledge is also manifested in their being more accurate than novices in judging the difficulty of a physics problem. We can argue that, in each of the above examples, the superior monitoring skills and self-knowledge of experts reflect their greater domain knowledge as well as a different representation of that knowledge."

Summary: This brilliant illustration by Efrat Furst best summarises this findings from this book.

Simply put, expertise is about knowing a lot about a specific area. It enables the expert teacher to see and act differently than novices.

"These investigations into knowledge-rich domains show strong interactions between structures of knowledge and processes of reasoning and problem solving. The results force us to think about high levels of competence in terms of the interplay between knowledge structure and processing abilities. They illuminate the set of critical differences highlighted in this overview between individuals who display more and less ability in particular domains of knowledge and skill. We interpret these differences as primarily reflecting the expert’s possession of an organized body of conceptual and procedural knowledge that can be readily accessed and used with superior monitoring and self-regulation skills."

Work cited:

Chi, M.T.H., Glaser, R., & Farr, M.J. (Eds.). (1988). The Nature of Expertise (1st ed.). Psychology Press. https://doi.org/10.4324/9781315799681