commented on in real life. In this latter respect, 'The book is on the table' is still relatively weak. A sentence like 'I need a taxi' (Taylor, p. 50) is potentially stronger because most people are more concerned about being able to verbalize this need than they are about being able to describe the most obvious location of a book.
In the same way, 'I need a taxi' is stronger for most students than 'I need a hinge. But other things being equal, strength is always relative to the needs and interests of the students: some people talk about hinges every day and never see a taxi. For this reason, we cannot build strength as a permanent and absolute quality into any fixed set of materials.
It is impossible to give simple directions for determining what would make materials strong for any given class.
Questionnaires may help, and being psychically 'with' one's students may help. Certainly it is necessary to be more than a purveyor of words and a master of drill techniques. This problem is discussed under 'specification' in Chapter 4 (p.13 5ff); pp. 21- 25 in Chapter 1 and pp.54 - 57 in this chapter also relate to it.
Lightness
'Is a single "unit" so long that the student wearies of it before it is finished, and loses any sense of its unity?' 'Does an individual line weight heavily on the student's tongue, either because of the number of difficult sounds or because of its sheer length?' Insofar as new words or structures, by virtue of their newness alone, make a line or a lesson tiring, they may also be said to contribute to its weight, but lightness is intended here to refer primarily to sheer physical characteristics. With respect to lightness, 'Your horse had been old' and 'I need a taxi' are approximately equal. Heaviness in this sense may vary with the language background of the learner: many would find 'I need
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