The other night I was sitting next to an Austrian teacher of English at a restaurant in Brighton, in southern England. He was a bit puzzled by an item on the menu which offered "Pan roasted local skate wing, crushed ratte potatoes, sautéed spinach, caper, lemon & parsley butter."

There might have been a number of things on that menu to confuse a non-native speaker, no matter how good, but the bit that puzzled our learned academic most of all was the reference to the skate wing. He knew both of these words, of course, but putting them together caused a bit of problem. He knew that the word skate was both a verb and a noun, but neither seemed to make sense to him within the context. Understanding the confusion immediately, it was pointed out to him that a skate is a species of fish. He remained slightly puzzled, merely asking with a wry grin if it was therefore true that, in England at least, fish skated?  No, we replied, and neither do they have much use for bicycles.

I was reminded that there is a classroom back home in Portugal which still bears the scars of my recent stewardship. The clock, for example, has plastic flies stuck over its dial. This is a visual representation of the potentially confusing expression, "time flies."  Clearly the word flies in this situation is a verb and not a noun, and the way I chose to express this was by displaying the opposite meaning. Call it aversion therapy if you like, for not many people like to see a clock covered with common house flies, and the other meaning seemed to be reinforced by this visual statement of the opposite.

From the classroom ceiling hangs a winged packet of butter (actually a block of polystyrene covered in the outer wrapping of a packet of butter). Ignore the man-made fibers and concentrate on the substance here. This model is intended to reinforce the dangers lurking within the humble word butterfly. What is a noun, and what is a verb?  Of course, context, as always, is everything, but what I was trying to demonstrate here was a visual presentation of the mental gymnastics that the language learner has to go through to "get" the meaning within the context. Most of my students did "get" the meaning. Some, alas, didn't, and I suspect that they are still in a state of slight ambiguous confusion. They react to a different kind of intelligence, perhaps, and I have let them down.

The presence of nouns that become verbs, and vice versa, and which are formed in exactly the same way, is a potential source of genuine confusion amongst our language learners. There are over 150 of these little blighters in regular use: drink, email, face, love, name, notice, shop, smile being just some of them. Bear in mind that I'm not referring to verbs that take on the role of a noun by the addition of suffixes like -ize, -ify, -ate or -en. That would add a whole new category.

A final verbal insult lies in the confusion between the verbs make and do, which continues to puzzle students in spite of explanations which explore the conceptual difference between creating and carrying out a task ("The teacher makes the test; the student does it"). All of this is blown to smithereens when students first get confronted with the expression make do, as in "If you haven't got all the pieces then you'll have to make do" — which, though presented as a verb, has all the qualities of a noun. It's a genuine tearing the hair out moment for English learners.

However, if all this wasn't confusing enough, contemporary use of nouns and accompanying verbs makes it all the more difficult for the learner to get a handle on the situation. To get to Brighton to eat with our Austrian colleague, I traveled by train, and, as we neared our destination, I was once again reminded of the concept-scrunching announcement that has become common on British trains, that "the train terminates here."  It grates with my concept of temporal reality, and each time I hear it I hope they don't actually mean what they say — because, presumably, if we mere passengers don't scramble off in time we, no doubt, will terminate with the train. Of course, what they mean is that the journey terminates, not the train, and though the context makes it clear, the association between noun and verb is likely to cause the same confusion for the language learner as skate on a menu, or flies on a clock. It won't cause panic amongst the language-learning train travelers perhaps, but it might insidiously cause a shift in meaning in their brains about the real meaning of the verb to terminate.

Does any of this matter?  It does if language teachers wish to remain coherent as custodians of the language, as English itself goes global. I can't pretend that my American cousins don't make it more difficult. In fact, the contemporary pervasiveness of noun/verb interchange which has seeped in from the American-dominated corporate world is causing some commentators to suggest that students avoid all use of verbs and nouns that are interchangeable, in case they get it wrong.

That is nonsense, of course, and would make the language all but impossible to use (imagine eliminating the use of the verbs/nouns I highlighted earlier). But the origin of this bad advice lies in a whole new swathe of words that are finding their way into usage as nouns and verbs: impact, parent, medal, and liaison are examples. As nouns they are familiar and useful, but as verbs they can sound clunky and unwieldy, though here we might just be venturing into the world of personal aesthetics or, at best, a lack of familiarity. The invented verb to parent, for example, is so ugly that users should be forced to wash out their mouths with soap and water. And why anyone would want to use the verb to liaison when there is a perfectly good verb to liaise in use beats me. I have made my position clear on this issue.

Recognizing the potential for ambiguity, then, we need to put these versatile words in the right and proper place for our students, and get them to spot the context that will give them the clue to the correct meaning. Hence my room with a plastic-fly-filled clock and decorative packs of butter hanging from the ceiling. I would be thrilled to hear of other ideas for models and mobiles to cover some of the other 150 plus verb/nouns in common use. I suspect, however, that our Austrian with a skate on his plate remained confused until his taste buds kicked in.