44 During a normal school (lay every child has to use and come to terms with a wide variety of printed materials. Not all of these are books: workcards, pamphlets, worksheets, extracts from journals or magazines are as common as books in some subjects. As teachers we are continually faced with the problem of choosing material appropriate to the needs of each child or group. Very often the need for something on a chosen topic is so specific that the question of choosing between alternative sources hardly seem to arise. Nevertheless, a teacher is always aware that a whole range of factors will determine how well a child will be able to cope with reading and understanding what is read. Some of these factors relate to aspects of the child himself, for example his vocabulary, previous knowledge and interest in the subject in hand, but it is also possible to isolate factors associated with the text itself. It is these factors which are often described in terms of the .of a passage; in general, they relate to aspects of a text which can be measured objectively in some way in order to predict the kind of difficulty we might expect a child of a certain age to encounter. This notion of predicting difficulty is important, since the whole idea of using readability measures is to take some of the guesswork out of one of the most difficult areas of judgement that related to the complexity of prose and vocabulary load.