Reader familiar with small children will know that they generally produce their first recognisable word round about their first birthday; from then until the age of about one year, six months, children,s speech consists largely of single words spoken in isolation. At this point, children start to form elementary phrases and sentences, so that a child wanting an apple at this stage might say 'Want apple'. From then on, we see a rapid growth in children's grammatical development, so that by the age of two years, six months,most children are able to produce adult-like sentences such as 'Can I have an apple'
From this rough characterization of development, a number of tasks emerge for the developmental linguist. Fristly, it is necessary to describe the child’s development in terms of a sequence of grammars. After all, we know that children become adults, and we are supporting that, as adults, they are native speakers who have access to a mentally represented grammar. The natural assumption is that they move towards this grammar through asequence of ‘incomplete’ or ‘immature, grammars. Secondly, it is important to try to explain how it is that after a period of a year And a half in which there is no obvious sign of children beingchildren being able to form sentences, between one-and-half and two-and-a-half year of age there is a ‘spurt’ as children start to form more and more and more complex sentences, and a phenomenal growth in children’s grammatical development. This uniformity and (once the ‘spurt’ has started) rapidity in the pattern of children’s linguistic