Key Words for Fluency Upper-Intermediate concentrates on those words which students need to communicate in English. It emphasises those very common words which occur in lots of different contexts and identi­fies around 150 nouns which are essential for fluen­cy. Each unit deals with one word and on average covers 20 of its most important collocations, teach­ing over 3,000 lexical items. Collocation is the way words combine with other words in predictable ways. Knowing strong and frequent collocations is essential for fluency.