We are all aware of the teacher shortages across Scotland, particularly north of the Central Belt. These are no longer only in certain subject areas but are increasingly across the board, and there is also a lack of supply teachers to fill short- and long-term vacancies.

I retired in August last year, after a 39-year career, including 18 years as a secondary headteacher. I had gone through the ranks of teacher, principal teacher, assistant headteacher (remember those?) and deputy head since starting my probation in August 1978.

I’ve also been on the council of the General Teaching Council for Scotland since 2012, and was convener from 2014-18. However, I am not quite ready for slippers and daytime television. Fishing and golf are not ideal through the Scottish winter. So how difficult could some supply teaching be?

The answer is incredibly hard, very demanding and stressful - particularly at the start. Which begs the question, how do you “evolve” from headteacher to supply teacher?

Getting on the supply register is the first hurdle. In the local authority I had worked for, this was straightforward - an application, PVG (Protecting Vulnerable Groups) check and references. Other authorities required an application, interview, yet another PVG check, two additional references and the completion of seven pieces of paperwork, not including the original application. The time taken should have been around six weeks from start to finish, but in my case it was a little longer owing to a holiday. (There’s no point in retiring and not going away outwith the school holiday times - it’s cheaper and quieter!)

Your past experience ‘means nothing to pupils’

So, having got myself on to the supply registers, I waited for the phone call, text or email. I have been approached by around eight different schools across two authorities. I have offered my services, when available, and worked in two very different schools. This is because, once you are known in a school and do a reasonable job, they want to keep you to themselves.

The first thing that you learn very early on is that knowledge, experience and previous professional status mean absolutely nothing to any group of pupils you are allocated. As far as they are concerned, you are just a “cover teacher” who is filling in until the “proper teacher” returns or the vacancy is filled. This is reinforced by one local authority issuing ID badges displaying the words “casual teacher”. I was asked about this by pupils and felt the need to explain that I was actually a “proper” teacher - I now have a white sticky label over the “casual” part.

The first big challenge is finding your way around the buildings. In relatively new schools, the numbering of rooms and naming of floors is usually fairly straightforward. In many others that have grown over the years, there are different blocks and numbers that don’t differentiate between floors. Once you’ve found the correct room, there are different passwords for ICT systems, the Seemis education management system, Google Classroom and email. These have different requirements in different authorities in terms of length and complexity.

I am certain there are “dark forces” at work making sure that the number and types of password are so complex that you have no choice but to write them in the back of your diary or have variations of the same one, neither of which enhance security.

Having found the class and registered them accurately (forget about remembering any names), you have a fighting chance of some actual learning and teaching commencing.

So, to the work set ... Notes sellotaped to the teacher’s desk appear to be standard practice, but are not easy to read while you’re wearing varifocals and standing up, and if you tear them off the desk, there is inevitably no spare tape to stick them back down for the next victim.

Some subject knowledge tends to be assumed - after all, we are teachers, so we know everything! In the past year, my knowledge has grown enormously as I have attempted to deliver lessons in history, modern studies, science, maths, English, PSE. I had a long stint at various technical subjects, including graphic communication, practical craft skills and engineering science. (I am qualified to teach geography and geology.)

However, in many ways, this is what I enjoy - every day really is a school day for me. I really like not being the expert. For example, while using Microsoft Publisher in a package design and marketing section of an S3 graphic communication course, pupils would ask how to achieve a type of drawing or shading. I would find a pupil who knew how to do this and get them to demonstrate the technique required - peer learning at its best, with the pupil tutor, the class and me all learning.

My development has also included mastering the Smart Board. A 10-minute lesson from a very helpful deputy head got me going and, wow, I wish they had been around in 1978, along with YouTube, which is an amazing source of materials to educate and motivate. I started on a roller blackboard, graduating to a whiteboard and overhead projector sometime in the 1980s.

My conclusion is that supply teaching is at least as demanding as being a secondary head. I never want anyone, including supply staff, to use the “just” or “only” as a prefix to describing a supply teacher. Will I continue? Yes, at the end of the day I am a teacher and don’t want to leave the profession. However, the term-time holidays will also continue - I am not sure I could get through a term without a decent break.

Derek Thompson is a former secondary head in Aberdeenshire who now works as a supply teacher