Many teachers were lured into the profession not just by a desire to educate young people but because it offered a chance to continue a passion: to indulge a love of maths, or science, or English, and to communicate that excitement to others.
Unfortunately, it is often the case that when teachers actually begin teaching, subject knowledge takes a back seat. Other issues - typically practical and focused on students or systems - take priority. The job tends to become generic, particularly in primary schools where even subject coordinators have little opportunity to explore any subject in depth.
The question is, does all this matter? Is subject knowledge important to our ability to teach, to be motivated and to enable learning? And if it is, what should school leaders be doing to cultivate and extend it?
The value of subject knowledge to teaching has certainly been emphasised in policy and research over the past 30 years. But what do stock phrases such as "mastery of the subject", which appear regularly in documents from governments of all persuasions, actually mean?
Academics and commentators tell us that subject knowledge needs to encompass the core content and frameworks that comprise a discipline, alongside the teaching methods and skills particular to that field.
It isn't easy to see how formal requirements, training and continuing professional development (CPD) currently mesh with this. In the UK, teachers are allowed to teach a subject they passed at A-level. Does this give them the requisite skill to make the subject accessible in lessons? It could be argued that even having a degree does not automatically provide the understanding required for the higher grades of school examinations; some university study can be very narrow.
So this is where CPD should come in: providing an opportunity to increase subject knowledge in carefully chosen areas, with instruction on how to communicate that knowledge to students. However, evaluations of CPD and school professional learning environments by the Centre for the Use of Research and Evidence in Education (Curee) suggest that this type of training is rare.
When researchers at Curee investigated CPD, they found it was increasingly being delivered via generic, whole-school Inset sessions. These might (or might not) have been rooted in research and evidence about effective learning, but more than 50 per cent of teachers spoken to by Curee said they struggled to see how these sessions had relevance to their practice.
In short, leaders may be trying to find ways of responding to teachers' diverse backgrounds and interests but too often they are struggling to connect with any of them.
The decision to handle CPD in this way seems to have little reasoning behind it. Across the world, research into effective professional development consistently reinforces the importance of accessing in-depth specialist subject expertise. A review of international research into curricula of all stripes found the same. (You can find a selection of these studies from Curee at bit.lyCPDReview.)
The findings show that concentrating CPD on subject knowledge gives teachers the confidence to share responsibility for learning with students. These teachers are also able to offer in-depth, open-ended enquiry, confident in the knowledge that they can draw discussion back to the primary goal. Secure subject knowledge also appears to remove dependency on textbooks and limited schemes of work, allowing for creative teaching that responds to the individual starting points of students.
So if we recognise that teachers require continuously evolving subject knowledge and professional expertise, how are we going to find the space and time to develop them both?
In Finland, teachers must complete a master's degree that includes both pedagogy and subject knowledge. The rest of the world is unlikely to go so far. But we can do much more to recognise subject knowledge as a valid part of CPD.
Make time to think
School leaders must ensure that teachers have opportunities to reflect on the impact of generic teaching strategies on specific subjects. For example, cross-curricular sessions (often designed to help colleagues examine alternative ideas) should include time to contextualise the implications for their individual subjects. Is this teaching style really appropriate for maths? Does this research have any relevance to English teaching? Questions like these should be an integral part of CPD.
Primary leaders can involve subject specialists (for example, from local secondary schools or universities) in whole-school sessions and then encourage phase or year teams to work together to contextualise subject knowledge for different stages of development.
Individuals can also take the initiative, even if encouragement to do so has been limited in the past. Secondary teachers can become examiners, a role which generates the most up-to-date knowledge about exam board requirements and introduces them to specialists from other schools.
Teachers can also take distance-learning courses. This may, for example, reflect current developments in English literature or allow a teacher to pick up on an era with which they are less familiar. Such opportunities advance subject learning as well as increasing motivation for teachers and potential gains for students. An alternative is to revive links with subject associations. Many of these are active in promoting subject research and have fantastic guides on how to do it within the constraints of a teacher's limited time.
Nurture professional links
Links with others who are passionate about a subject, perhaps in more practical ways, are important too. Relationships with a local further education college can be powerful here. For example, a recent recruit whose opportunity to teach a subject at higher levels is limited in school may find it is possible to lead an A-level evening class instead. At the other extreme, where there is only one teacher of a subject in your school, a local college might be a great source of mentoring. Primary schools that already have links with FE colleges to train classroom and nursery assistants might well be able to use those connections to make contacts with other departments.
Teachers who tweet often request information about real-world projects that are relevant to current curriculum goals. Other schools across the country, as well as people running community and environmental projects, seem to be only too pleased to respond with links and suggestions. Check out #Edchat on Twitter to see how this works.
Regardless of the route that is taken, seeking to retain relevant subject knowledge is as important as improving planning and practical skills. Given the compelling evidence, it is disappointing that so many school leaders opt for CPD that is at best irrelevant, and at worst a complete waste of everyone's time.
Philippa Cordingley is chief executive of the Centre for the Use of Research and Evidence in Education (Curee) and Graham Fowler is a researcher, writer and consultant
Cordingley, P, Bell, M, Rundell, B et al (2003) The impact of collaborative CPD on classroom teaching and learning (EPPI-Centre)
Bell, M, Cordingley, P, Isham, C et al (2010) Report of Professional Practitioner Use of Research Review: practitioner engagement in andor with research (Coventry)
Centre for the Use of Research and Evidence in Education (2011) How can school leaders manage curriculum change effectively? (Curee)
Cordingley, P and Buckler, N (2013) Who You Gonna Call? Evidence about using specialists effectively and who they are (Skein)
Cordingley, P (2012) The role of professional learning in determining the profession's future (Curee)
Is there a "crisis in understanding"? This TESS article looks at the arguments.
Explore the importance of subject knowledge to maths teaching.
We discuss the UK's shortfall in subject expertise.