Describe a spiral staircase. It's a challenge my technical drawing teacher, Mr Dickinson, used to put to the class.
"Well, sir, it's a staircase, and it goes round and round."
"What? It rotates?"
"Er, no. But it does go round and round."
His point was that there are certain things that are difficult to describe, and easier to draw, which is where TD comes in.
A drawing, or drawings, can make everything clear beyond doubt.
I had a classmate, John Parr, who was really good at drawing. In my young mind I thought I had discovered the reason that he was so much better than me. It was because he had a special pencil.
While the rest of us had bog standard pencils, John had not so much a pencil, as a machine. I think his dad may have been a draughtsman.
You pressed a button at one end and the other end opened out like a claw and grabbed the lead, of which there was a selection.
It was blue, and I think it was made by Staedtler. The button incorporated the sharpener.
If only I could have such a pencil, I thought.
Incidentally if you are rubbish at drawing, there are techniques you can learn. My dad could draw well, but seeking further self-improvement he got out a book which introduced him to the method of drawing upside down.
The thing is, if you draw something the right way up your brain knows what it should look like and interferes with the process, mucking up your drawing. But the theory, which does work, is that if you draw it upside down it doesn't look like anything, it's just a series of lines and curves, and so you draw more accurately.
Mr Dickinson is also the reason that I have never forgotten the date of the Magna Carta. It was in 1215 – when the dinner bell went.
The topical gotcha! question at the moment is not about describing spiral staircases, but is directed at Labour politicians and asks them to define a woman. (For Tory politicians the gotcha! question is to ask them whether somebody who lies in Parliament should resign).
In day-to-day life the "define a woman" question is not something that troubles 99 per cent of the population, any more than they would expect to have to define, say, a pomegranate while out shopping, or define a sofa in a furniture store.
There again, advances in science and medicine have raised new issues, and when there are politicians who have sought to inhabit this new territory and make rules, it is surely fair to ask whether they have a map.
There are answers that can be given. "Define a woman." "Why?"
Or "Define a woman." "Don't be soft."
Or you could make a joke. In the movie As Good As It Gets, Jack Nicholson's novelist character is asked by a young woman how it is that he writes women so well.
"I think of a man. And I take away reason and accountability," he replies.
Not that I would recommend that a politician made any such joke. Will Smith's biffing of a comedian who made a joke was emblematic of our age of offence and insult, and any politician making a joke risks getting similarly biffed, metaphorically speaking.
So far those politicians challenged to define a woman, including Sir Keir Starmer, have not attempted to do so, and consequently have been mocked.
Their reluctance is because they recognise that it is a trick question, and any serious attempt to answer will cause upset to somebody.
Dogged interviewers will need a new approach. "Okay, you won't define a woman, but here's a piece of paper – can you draw one?"
Upside down, for most accurate results.
A near neighbour who had planned a family history trip to Lviv is not now going, for obvious reasons.
Places in Ukraine which I, for one, had never previously heard of, are now familiar around the world.
As it happens I had heard of Lviv, albeit as Lvov, as it appears in older history books. It's also been called Lemberg, underlining its rich and complex past.
One thing I have learned through my neighbour's connection – and it came as a surprise – is that Lviv was once ruled by Poland.
There are people who think history is old hat. But it can be the key to real understanding of nations.