Teaching word origins

Some time ago, I recommended a site called developingteachers.com and told you that their weekly email tips were worth reading.
Sign up, I'm sure you'll find something interesting to do with your students.
This week's tip, although a good one, could have been developed more fully, especially for those of us who teach English to speakers of Romance languages. We aren't all in Thailand and Japan, you know!
The teaching tip makes the valid point that learning vocabulary can be more interesting for learners if they know something about the origin of the word. I couldn't agree more, as etymology is some that I love - I could spend hours just flicking through a dictionary or my copy of Brewer's Phrase and Fable.
The email goes on to give an A to Z of some interesting words and their origins. My concern is that although word origins are interesting, they won't necessarily help a learner to recall new vocabulary if they don't create a spark that ignites a chain of thoughts leading to the actual word being summoned up.
For example, the first word on the list is 'avocado'. If my French student was looking for this word in English, he might well remember that the origin of this word was 'testicle' in some south American language, but would that help him to remember the word 'avocado' itself?
When I was a child there was a very famous series of television commercials for a type of Vermouth (fortified wine) featuring the British comedian Leonard Rossiter and the even more well-known Joan Collins (of Dynasty). Research showed that although everyone who had seen the commercial could remember how funny it was, even the exact lines of the two actors, very few could remember which drink it was promoting: was it Martini or Cinzano?The advertisers had neglected the product in favour of a very funny ad. This could happen to a word with a memorable history.
Going back to example of avocado, if your learners are speakers of Romance languages, they will probably recognise that it's also the Spanish word for 'lawyer'. The Spanish colonialists heard an indigenous word that sounded a bit like 'avocado' (not very much like it in reality) and started to use it. When the fruit travelled the Atlantic to Europe, the French heard the Spanish using the word 'avocado' - (lawyer) and translated it to French: 'avocat' (just like English, 'advocate').
Another word on the list was 'umbrella'. Here is the definition:Umbrella, appeared in English as early as 1609 (in a letter byJohn Donne). In the middle of the 18th century the device was adopted by the philanthropist Jonas Hanway as a protectionagainst the London rain.There is no etymology here, just the date that it entered the English language. It would have been more pertinant, perhaps, to mention that umbrella comes from Italian 'ombrello' which relates to 'shade' not rain, and in fact was used to protect against the sun, not the rain. A French speaker would quickly recognise the word 'ombre' (shade or shadow) in his own language from the word umbrella, in fact, an old word for 'parasol' is 'ombrelle'.
The last word that I find could have been exploited more - at least for Europeans - is 'walnut'. I was surprised to discover that it means 'foreign nut'. But I did know that 'Wales' and 'Wallonie', a region in Belgium, are from a word that the Romans used to describe non-Latin speakers, hence foreigners. These words are also related to the French 'Gaul', as the Norman invaders of Britain had a strange way of pronouncing the letter G, it sounded to them like a W.