How long do things take?
Some things you can estimate with a reasonable degree of accuracy. I used to have to ask software engineers to estimate tasks in manhours; some were better at this than others, but they were usually pretty close – anyway, within an order of magnitude.
Teaching is another matter entirely. Teachers for various reasons like to have some idea how long things are going to take, but my best estimates go wildly awry. How long will a particular task take in a given lesson? How long is a piece of string? Oh, that long.
Sometimes you get it wrong through misplaced optimism. I used to have a colleague, an American called Bill, who complained one day that he had spent three hours – three hours! – doing his washing, cleaning his room, and cooking lunch the previous weekend. Three hours seemed about right to me. If you do those things, it’s hard to see how it will take much less time. Similarly in a lesson, I will plan to start with a quick review of a given structure (the present perfect!), and find the whole lesson get stuck there.
But at other times, it the fractal nature of communication which is the problem. You mention something, and it leads to something else, and to something else; points arise, language is consolidated or opened up, the quagmire of all English vocabulary is ventured out upon; you do not move through the lesson so much as get sucked infinitely into some singularity at the heart of it. A five-minute activity ends up weirdly bigger than the lesson it was supposed to introduce.
You can set limits, point at the clock, shut people up and shunt them (and yourself) along; you can be rigorous, disciplined, organised. You can, if you teach like a muleteer, get through stuff. But since, as I believe, most language and communication are a form of digression, and that you may as well talk about this bit of language that happens to be under your nose as any other bit of language, I find, in the end, I just don’t.