Children's Acquisition of Language 

Syntactic Development.

We can start to speak of children's syntax when they reach the duose (two-word) stage. When two words are put together, we can speak of the interaction between them being syntactic. However, the context, intonation and gesture are needed to clarify meaning, since an utterance such as ball here could be declarative, interrogative or imperative. 

During the duose stage, children seem to be able to put words together in constructions that look like subject+verb, e.g. baby play and verb+object, e.g. want ball

Early in the duose stage, words-endings are missed off, for example the -ed past tense ending is omitted, and this may continue throughout and beyond the duose stage. As the telegraphic stage is reached, children may oversimplify (or overgeneralise) the use of inflectional morphemes, e.g. foots for feet, winned for won. 

As children start to put together more than two words, they enter the telegraphic stage, and gradually the mean length of utterance increases. At first, function words such as articles and prepositions are missed out, as are many verbs, especially auxiliaries (hence the name 'telegraphic').  By the age of about three, most children will be using these grammatical categories reasonably fluently.

 The development of questions.

At the holophrastic stage and in some cases at the duose stage, the child uses intonation rather than syntactic structure to indicate a question. During the second year, the child starts to use the interrogative words what and where, followed by the acquisition of why, how and who. At this intermediate stage the article will be missing, e.g. where ball? and the word order will be the same as for a declarative, e.g. ball's here? It is with the acquisition of the verb to be and the development beyond the telegraphic stage that the normal word order for questions can be used, e.g. where is the ball? Is the ball here? Most children have mastered this by the age of about three.

 The development of negatives.

The first stage is where the child puts no or not at the beginning of the utterance, e.g. No play, followed by a stage where the negative morpheme is put within the sentence, e.g. Me not play. It is with the acquisition of auxiliaries that adult word order becomes possible, e.g. I won't play. Most children have reached this last stage by their fourth year.

 Putting clauses together.

At about the age of three, children start linking clauses together. The co-ordinating conjunction and, subordinating conjunctions such as because and prepositions such as before are  commonly heard during the fourth year.  

Moving towards adult syntax.

Between the ages of about three and half and about four and a half, children start to master irregular verbs and plurals, and such forms as foots and drawed gradually disappear. Correct forms of pronouns will also start to be used regularly, and forms such as me or him cease to be used as the subject of the verb. 

By the age of five, most children use speech which for the most part conforms to the norms of adult syntax, although certain more complex structures both within and between sentences will continue to evolve for perhaps another eight or ten years. 

C D Selwyn-Jones 2003