Experts are people with vast, complex and refined ‘mental models’ of their domains of practice. Mental models refer to what someone knows and how that knowledge is organised to guide decision and action in a specialist context. If we wish to systematically develop expertise in teaching we need to have a clear understanding of the mental models that expert teachers possess and how they are developed.

How might we go about gaining such insight? One way is to look sideways to other sectors who have made progress on this problem. One such field is medicine. There are clearly important differences between teaching and being a doctor, but there are also sufficient similarities to make it worth exploring what medical expertise looks like and how it is developed.

In very general terms, doctors develop expertise by learning a body of knowledge (human biology, anatomy etc.) and then re-organising that knowledge around the day-to-day practice of being a doctor (Schmidt & Rikers, 2007). This process is called knowledge encapsulation, and over time, consistently produces professionals who can take a highly complex and subtle set of cues about a patient, and make an accurate diagnosis about how to help them get better.

The process of knowledge encapsulation requires significant investments of study and deliberate practice, and in reality is much messier than the crude model outlined above (Kalyuga et al., 2012). However, it appears to be a relatively reliable approach for enabling expertise in a highly complex practice at scale. The practice of teaching is at least as complex as medicine, but our understanding of and systems for developing expertise are less developed by comparison.

Developing teacher expertise is important. It’s our strongest lever for improving the experiences and life chances of the pupils in our care. If we are to increase the prevalence of expertise across our profession we need to get serious about understanding the mental models that expert teachers need, and how they can be developed (Deans for Impact, 2017). As part of this, we need to think hard about what teachers need to know and in what order, alongside the pattern of experiences that will help them encapsulate that knowledge around their practice.


Deans for Impact (2017) Practice with purpose: the emerging science of teacher expertise.

Kalyuga, S., Rikers, R. & Paas, F. (2012) Educational implications of expertise reversal effects in learning and performance of complex cognitive and sensorimotor skills. Educational Psychology Review, 24, 313–337.

Schmidt, H. & Rikers, R. (2007) How expertise develops in medicine: Knowledge encapsulation and illness script formation. Medical Education, 41(12), 1133–1139.