However, even though 'carefully designed', a single coursebook can never completely meet the needs of a specific class of learners, but will often necessitate the integration of additional material to 'bridge the gap' between what the coursebook offers and what the teacher knows the learners still need, be it more practice of a particular grammatical structure, exposure to more 'textual material', use of 'differentiated material' for different levels of proficiency, or more use of activities for affective purposes and motivation (ibid:80-81).
