Qualities of a Good Explanation

A good explanation should:

be correct
It is surprising how many incorrect explanations you find in TEFL books. A good example is the distinction usually made between some and any, which goes something like:
Use some+plural countable/uncountable noun in affirmative sentences.
Use any+plural countable/uncountable noun in negative sentences and questions.
Higher level books may go on to add that you use some in questions if you expect an affirmative answer, or in invitations, or various other situations. Not only does this ‘rule’ score low on generality, it still fails to explain:
Take any one you want.
Any of the assistants at the desk will be able to help you.
I didn't like some of his books.
Compounds (somebody, somewhere etc) also create problems for this explanation, as many of them have to be explained separately.

An explanation based on the difference in meaning between some and any might eliminate many of these problems. Such an explanation might be along the lines of:

any+noun refers to an indeterminate subset of the collection of nouns referred to.
some+noun refers to a particular subset of the collection of nouns referred to.
This explanation is not particularly clear here, but can be made so by being presented in an adequate context. It does have the advantage of being a reasonable approximation to what the difference between some and any actually is. See 'some or any?' for an example of such a presentation.

The advantage of the traditional explanation is that it is easy to teach, which can be important for lower level classes, multi-lingual classes, and classes given by inexperienced teachers. However, ease of teaching should not be a prime concern - it is the teachers job to get their head around such problems. Ease of learning is more of an issue, but I don't think this is promoted by giving explanations which students will soon see being contradicted. At lower levels, if you must give an incorrect explanation, a lot of problems will be saved if you make the limitations of your explanation clear. In the above example, you might give the first explanation as a ‘rule of thumb’, emphasizing that, although it provides a guide for most situations, it is not to be considered a hard and fast rule.

be consistent
Fairly obvious this. An explanation shouldn’t contradict itself, or any other explanations the student might have been given. Of course, if the student has previously been given an inadequate explanation (such as some/any referred to above) then you are going to have to contradict what they have learnt.

be simple
The explanation should be as simple as possible, but no simpler. Never over-simplify - again, some/any is a good example of this. The problem is that students soon come across examples that contradict what you have taught them. Obviously, the explanation also has to be comprehensible, which may provide problems for lower levels or younger learners. If you can't come up with a suitably comprehensible explanation, maybe the structure in question is not suitable for the level you are teaching.

have no exceptions
An explanation with exceptions is going to create problems as soon as a student comes across one of them, and then says 'but you told us...', which leaves you looking pretty silly. You should explain how apparent exceptions fit in with the rule you are teaching, or, if there are dealing exceptions to the rule you are teaching, you should point them out to students. For example, you might explain that the present perfect is never used with adverbs of finished time, but you should also point out that 'just' is not an adverb of finished time (something that has never seemed immediately obvious to me!)

be complete
Each of the following explanations for the present perfect is more 'complete' than the one preceding it:
The present perfect is used to describe experiences.
The present perfect is used with adverbs of unfinished time.
The present perfect is used for actions which can still happen, or can happen again.

How well do they explain:

I've been to Paris.
I had cornflakes for breakfast today.
The teacher hasn't arrived yet.
I've done my homework.
The first three examples can be explained by the third explanation given above; the first two explantions fall down at the second an third examples. The third explanation can cover all three examples and so can be considered complete in the sense that it explains all similar situations without any need for 'speacial pleading'. The fourth example, however, cannot be explained by any of the above explanations, and requires treatment as a separate situation or 'use' of the present perfect. See my page on the present perfect for a full analysis of situations where the present perfect is used.

be exhaustive
At lower levels it's fairly normal to leave out some of the more subtle details; at advanced levels this is not really an option as if you don't give the students the information you can't assume anyone else will. For example:
It's years since I went to Scotland.
It's years since I've been to Scotland.
The first form would be included in most explanations (since + point in time), the second requires a bit more effort. If you compare the following examples, however:
It's years since I left school.
INCORRECT *It's years since I've left school.*
it becomes clear that the present perfect can be used after since only if the action can still happen - I can go to Scotland again, but I can't leave school again. This is the kind of explanation which, despite being simple, is omitted by most TEFL books.

Another example:

INCORRECT? The car was too fast for me to follow it.
The car went too fast for me to follow it.

Why can't 'it' be included in the first? Because here fast is an adjective and complement of the subject. In the second sentence fast is an adverb, and as it doesn't describe the subject we need to include an object for 'follow'. This is another explanation which is conspicuous by its absence from most TEFL books.

A slightly differentproblem is that with some structures, such as inversions, there are a lot of different cases to cover - it's difficult to be completely exhaustive.

be general
The explanation should be at the most general level possible. For example, we often teach that 'will' is not used in if-clauses. However, this is just a consequence of the fact that we don't use 'will' (for future reference) in subordinate clauses. By teaching the latter, possibly in the context of a lesson on conditionals, you are giving the student information which is much more widely applicable. The end result is that the student has a lot less to learn. You also avoid giving the (false) impression that English is a language that is full of exceptions and ad hoc rules.

be productive
No matter how good an explanation is, it's not much use if it leaves the student asking 'why would I want to say that?' The passive is a good example; it's fairly easy to explain the syntax, but unless you give examples of where it is usually used, students aren't likely to use it very much. In general, explanations along the lines of 'this structure emphasises...' are not very useful for helping students to decide when to use a structure. 'The present perfect continuous emphasises the activity...' is a typical example. How does this help us to choose between:
I've chopped the onions.	
I've been chopping onions.
Not very much. When to use one form or the other becomes much clearer if you explain that each sentence refers to a differnet type of result, so:
I've chopped the onions.    (They're ready to fry.)
I've been chopping onions.  (That's why I'm crying.) 
With this information, students can choose the form to use depending on the message thay actually want to get across.

enable discrimination
This is similar to (the same as?) the previous point. The explanation should enable students to discriminate between when to use one structure and when to use another. For example, you should teach students the difference between If only and I wish. If you don't, how can they choose which to use in a given situation? The obvious problem here is that it can be very difficult to explain subtle differences between forms - assuming you can work out the difference. Examples:
I wish you hadn't done that.	
If only you hadn't done that.
The first sentence regrets the effect your action had on the speaker, the second expresses regret for the effect it had in general. The second, unlike the first, can be used to express sympathy.
I wish I had studied harder.
If only I had studied harder.
In the second sentence here the negative effects of my not studying are being felt now or 'immediately'. The first sentence might be referring to a negative effect at some time in the past.
I wish he didn't go on so much.
I wish he wouldn't go on so much.
The first sentence expresses regret about a fact that the speaker doesn't like. In the second the speaker also shows that he would like the situation to change. A full understanding of how we use will and would are required to analyse the second sentence, although it usually include in sections on wish/If only.

be 'memorizable'
A good explanation should be easy for students to remember. This is not likely to be the case for long and rambling explanations, or for those that require students remember lots of arbitrary information, such as the explanation for adjective order found in most books - can you remember the order?

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Colin Mahoney, cmahoney@readysoft.es

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Last update: 1/04/96