My Sunday paper of choice has a games section which includes two Sudoku grids - a "standard" and a "fiendish". I have occasionally tackled the easier one, with occasional success. The most frustrating part of the process is when the end appears nigh and you realise you have blundered and it's not going to work. At that point, I decide to complete the adjacent crossword with its helpful "dual-speed" clues and the calming influence of words rather than numbers.
It was with some trepidation, then, that I faced up to the final task of my short secondment as an acting depute head - the school timetable. The motivation for including this as a target in my professional review and development interview seemed laudable at the time. Given the importance of curricular structures for the delivery of the secondary curriculum, and my involvement as EIS education convener in the development of Curriculum for Excellence (CfE), I wanted to be able to opine on these matters with authority and experience.
Be careful what you wish for! The world of compatible triples, incompatible pairs, and cross-setting matrices is cold and harsh. You begin with lofty ambition about meeting the needs of the curriculum and end by trying to justify absurd class combinations with the pathetic excuse: "But it fits in!" Did I forget, until it was too late, that home economics has to have double periods and be blocked early, while there is still space? Cross words, indeed, and most of them unprintable.
And it's obsessive. I have not been as driven by a single project in my career as the need to complete the timetable. Only when the task was done could I finally be free - and now, 1,742 data entries later, I am. Well, almost - I have put out the draft and await the verdict of my peers.
As a principal teacher, my previous involvement with timetabling meant arguing our department's case for more staffing, extra periods or the need for continuity. Other departments were seen as the enemy, seeking to gain advantage at the expense of English.
So perhaps the biggest insight I gained from the experience is a realisation of the complexity of the curriculum that young people engage with in schools. There is a lot going on. Creating a sense of coherence around that experience is paramount - which is what interdisciplinary learning is about; staff and pupils making connections across teaching and learning.
There is a worrying trend in some schools where interdisciplinary learning is appearing as a timetabled slot. Often what is labelled as such could be called multidisciplinary - various subjects making discrete contributions to a common theme. There may be merit in this type of project, and pupils may be engaged by it, but it lacks the depth that effective interdisciplinary working achieves.
Like most of CfE, it is not about "big bang" approaches; it's about small connections: S3 English classes reading Carol Ann Duffy's Shooting Stars to coincide with RE's study of the Holocaust; Higher modern studies and Higher English teachers using the same language to explore critical essay skills.
I spoke once about secondary teachers getting out of our subject silos and received an angry letter. I wasn't suggesting we abandon our posts; simply that we engage in a little fraternisation. Proposals to weaken the role of subjects should be resisted, as interdisciplinary learning requires the foundation of disciplines, but making progress on connecting learning across the curriculum is essential.
Despite my new-found respect for things mathematical and precise, ultimately a timetable is simply a necessary mechanism for structuring the delivery of the curriculum - the real trick is getting it right.
Larry Flanagan is education convener of the Educational Institute of Scotland.