Strength
'Does it carry its own weight by means of the rewards that it makes available?' As we pointed out in Chapter 1 (p. 23f), rewards may be of at least five different kinds; they must be valid in terms of the values of the learner, and not of the materials writer only.
In the evaluation of an entire course, concern about strength will lead to such questions as:
Looking at a single lesson from the same point of view, one may ask:
On the smallest scale, a sentence like 'your horse had been old' (cited by Jespersen, 1904) is weak to the point of being feeble, because there is no situation in which anyone can use it. The cliché 'The book is on the table' is stronger, because the situations in which it can be used are fairly frequent. But we must distinguish between the ease with which a situation can be created in the classroom, and the frequency with which it actually gets
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