Occasionally you might be tempted to show your class a video.

Videos look great in theory. The teacher bungs one on, tells the students to prepare comprehension questions for each other (so he does not have to) and falls asleep in a darkened corner. The students would far rather watch a film than do grammar exercises and readings, so they will be happy.

Life in practice is seldom so simple. The first problem is finding a suitable video. Your school possesses eight, all of which the students have seen several times. If they have not watched them in a lesson, they will have done so at home.

Perhaps you have bought a video for your own amusement and you bring that in. However, you must not forget one of the golden rules of teaching: anything the teacher likes, the students will not (and vice versa). A film released before 1990 might as well have been made during the Punic Wars. Students will stare at you in horror and cry, “I not borned then!”

Another problem is language. If the film is subtitled in the local language, the students will derive negligible benefit from watching it. If it is not, they will not understand a thing.

In some countries you have to be very, very careful about the slightest hint of a suspicion of a whisper of an iota of a whit of a smidgen of smut. If you show an ostensibly innocent film like A Fish Called Wanda during Ramadan, do not be surprised if your students storm out en masse.

Let us imagine that, despite these difficulties, you have decided to go through with it. You have your film and you are prepared to ignore any objections from the students. The next problem is the equipment. There are VHS and Beta videocassettes. There are VCDs and various flavours of DVD. The pirated disks that work perfectly well at home fail to do so on the elderly machine at work. And so on. You explain these complications in the local language to the school porters. After a lot of mime and a few false starts (they try to sell you a pornographic video, they remove the tape recorder from your classroom, they think you have given them the school’s video player and are overjoyed), they trundle the equipment to the classroom and connect all the cables.

The students arrive. For a moment they are excited, until they see which video you have chosen. Groans. You explain the task. More groans. You switch on the video. Nothing happens. You try other buttons. Nothing. The students watch impassively. This is, after all, more entertaining than the film is likely to be. In the end you give up and fetch the school porter.

You are now in the highly embarrassing position of having to talk to the porter in front of the students. While he is not thrown by your attempts to speak his language, the students find it hilarious. Now they can get revenge for all those lessons on the ing form, sentence stress, phrasal verbs. Every word you utter provokes gales of incredulous laughter and is repeated in a savage parody of your accent. Bright red, you huddle over the machine with your back to them.

Eventually everything works. The film starts. Students immediately make derisive noises about the actors, the sets, the costumes, the film quality, the sound, and so on. They ignore the task and keep up a background commentary in their language.

Films are about the same length as English lessons. This means that, by the time you have got it started, the film will overrun by ten minutes. Students will not stay in an English language classroom 30 seconds more than necessary. You will have to split the film over two lessons (meaning a repeat performance and more groans) or skip the ending.

After a video lesson most teachers clutch the student book to their bosoms like a lost teddy bear and vow never to spurn it again.