American television is responsible for the near-death of the practical joke. US comedy series rely on witty answer, obvious (but funny) answer, child- telling-the-gosh-truth answer and plain slapstick – hide in cupboard, found in cupboard.

What happened to practical jokes? Are they still out there? They must be but I do not see them. They are important. During the Second World War, both the Allies and the Germans used practical jokes for warlike purposes. In North Africa, German general Rommel had his engineers make up a huge park of vehicles covered in canvas, which looked like poorly concealed tanks. From the air, they just looked like wooden crates covered with canvas (which is what they were) but in reconnaissance photos, the British saw, poking out from the canvas, the occasional tank track, gun, turret ring, all of which made them say, oh, no, Jerry boy, you want us to think they are just wooden crates? We can see that your careless covers show that they are, in fact, tanks.

The perfect practical joke? Okay, well, perhaps just good but not perfect. Knowing the thoroughness of the German armies, the Brits should have questioned if it was ever possible for a German to leave any tank track exposed by accident. If it was me, I would guess ‘no’.

Practical jokes are important, not only in war. A good electrical engineer will curve the streetlight positions around a bend such that the curve will seem obvious to a motorist at night. In fact, the curve will be slightly wrong – were it to follow the exact road radius, then the motorist might well visually lose the curve line.

Most of all, practical jokes are important because they are fun and teach people to think. Students who come to us to do vacation work have a joke programme. This is apart from the actual engineering training programme. Firstly, Tim pretends to forget the name of the student. Every day, he comes and asks me what the student’s name is. Just in hearing range of the student, I tell him, but slightly wrongly. Thus, if the student’s name is Siba, I will tell Tim his name is Sipa. As the weeks go by, we change this to Ziba, Zorba, Stamza, and so on . . . until the student points out his actual name. Very funny, but it does make the student realise that, if you do not introduce yourself, nobody else will.

Next, we teach the student how to measure sound with a sound-level meter. Not too difficult and, after a while, the student develops an “Oh, hum, is this all there is to this atti- tude?” Then we ask the student to measure the frequency spectrum of a dog barking – specifically, my cocker spaniel, Thompson. Now Thompson has a sister, Sophie, and, if they do bark, it is always together. But often they do more sleep than bark. Days pass while the student, on a hair trigger, tries to record barking opportunities. Finally we give the clue: put Sophie in the office, take Thompson to the gate, leave him inside the grounds, walk off and leave the sound level meter running. Barks like mad. The student realises that what sounds simple is not always so.

We also send the student to record the sound of a vuvuzela. It takes a morning before it is realised that this is a two-person operation – one to blow and one to read the meter. Thus, analyse the task before you try to do it.

I could go on with all such ‘gawsh, that’s cute’ stories, but I have a serious intent – young people now learn from the Internet and little from a ‘learned experience’. Internet learning does not stick. Learning by practical joke was once a long- established way of teaching apprentices (as in sending the appy to get striped paint, a left- handed shifting spanner or just to go to the workshop to get a long weight (geddit? Wait/weight . . . Ha!) Now it seems that learning experiences are all ‘read this and write the exam’. So boring. Shouldn’t be – practical jokes are much more fun and teach better.