Idioms are usually defined as groups of words whose meaning is different from the individual words. So, ‘under the weather’ has nothing to do with the literal meaning of ‘the weather’; it means ‘feeling ill’. If you ‘sweep something under the carpet’, you try to keep something secret; and if you put someone in the picture, you give them the information they need to understand a situation. As these examples illustrate, in some idioms the meaning can be almost impossible to guess out of context, while others are more transparent.
Phrasal verbs consist of two and occasionally three words: a base verb and at least one particle (preposition or adverb). Many phrasal verbs are idiomatic: in other words, the meaning of the verb and particle is different from the base verb on its own. For example, the meanings of give up and give in are quite different from the meaning of give. As with idioms, some phrasal verbs are more transparent then others, e.g. stand up and the most common meaning of stand are very similar in meaning, as are sit down and sit. In other words, phrasal verbs can be seen as a type of idiom, although they are often singled out for specific attention in language-teaching materials.
Putting idioms and phrasal verbs together has a linguistic rationale, but perhaps an even greater pedagogic one. A relatively short passage of text – a practical necessity in most language-teaching materials – does not normally produce nine or ten naturally occurring phrasal verbs, but it can easily yield that number if the target language includes both phrasal verbs and idioms. This makes it easier to present the target language in continuous text rather than disconnected sentences, and gives learners more opportunity to see the expressions being used naturally, and to use them themselves in a realistic way.
When people think of idioms they tend to think of the more imaginative and colourful examples: kick the bucket, have a bone to pick with someone, full of beans, be barking up the wrong tree, etc. These vivid expressions can be extremely difficult to understand, so they are often the ones that teachers are called upon to explain in the classroom. It is also undeniably true that idioms, especially the more vivid ones, hold a particular fascination for some learners. However, there are thousands of idioms, less exotic and often more transparent than the ones above, which are of higher frequency and probably greater value to the vast majority of learners. Here are some typical examples: bear sth in mind, get your own way, by far, come in handy, fair enough, a happy medium, have your doubts about sth, hours on end, I thought as much, if all else fails, in all probability, last but not least, leave it at that, life’s too short, little by little, no wonder, not necessarily, odds and ends, on the surface, play a part in sth, rightly or wrongly, so what?, take it personally, that’s life, the sooner the better, to put it mildly, two years running, use your head, you’ll be lucky.
Some of these will appear so mundane that they often pass unnoticed as idioms. In some cases the meaning may be quite easy to guess, especially in context, but the same concept may be expressed in a different way in the learner’s mother tongue. Thus, these expressions need to be learnt and are equally deserving of our attention.