Identfiying stages

Discovering the words of a language, and what they mean in the world, is only the first step for the language learner. Children must also discover how the distribution of these elements, including grammatical endings (-s, -ed, -ing) and function words (of, to, the) convey the further combinatorial meaning of an utterance. That is, children must implicitly discover and use the grammar of their language to determine who-did-what-to-whom in each sentence. (Saffran, 2001)
In the formation of questions, use of negatives, there appear to be three identifiable stages. The general pattern is that stage 1 occurs between 18 and 26 months, stage 2 between 22 and 30 months, and stage 3 between 24 and 40 months. (Yule, 2006) By observing the changes in questions, negatives and morphological developments, I have divided the children X, Y and Z into the three stages.
CHILD Z:
• No picture in there.
• Where momma boot?
• Have some?
Child Z is at the earliest stage which may be between age two and two and a half years. At this stage, children form negative statements by putting no or not at the beginning which is why when claiming that there is no picture, the child says “No picture in there”. Secondly, while formulating questions the child’s first stage has two methods. Simply add a Wh-form (where, who) to the beginning of the expression like when inquiring his mother about the boot, the child says “Where momma boot?” Another way of asking a question is to simply utter an expression with a rise in intonation towards the end. The statement “have some” has been converted into a request type question “have some?” by the stage one child speaker. In terms of morphology, a few grammatical inflections appear and simple prepositions like in, on connect the lexical morphemes together e.g. “No picture in there”.
CHILD X:
• You want eat?
• I can’t see my book.
• Why you waking me up?
Child X is in the second stage of development because now the questions are more complex expressions but the intonation strategy is still being used as in “You want eat?” More Wh are also introduced by the child like the Why in “Why you waking me up?” In the second stage, the negative forms don’t and can’t appear and the no and not are used in front of the verb now, rather than at the beginning. This is shown in the sentence “I can’t see my book”. In terms of morphological development, inflectional morphemes indicating the grammatical function of nouns and verbs start appearing in the child’s language and usually the –ing expression appears as depicted in the third expression uttered by child X. (Yule, 2006)
CHILD Y:
• Where those dogs goed?
• You didn’t eat supper.
• Does lions walk?
This child seems to be in the third stage of development because the questions uttered are quite close to the adult model. In the declaration “You didn’t eat supper” the child is conveying a negative message by using auxiliary verb form “did not”. The typical negative forms of stage one have disappeared. Also, a couple of morphological developments can be noticed such as marking of regular plurals with the –s form, as in lions and dogs. The word “go-ed” proves that regular part tense forms that typically precede the appearance of the –ed inflection have also appeared but the child is over generalizing that version by saying go-ed. In the question “Does lions walk?” the child is using the –s marker on third-person-singular present-tense verb and this is apparent in the auxiliary usage of “Does”.
Looking for distinctive features, inflectional categories, syntactic rules, and all the dozens of other possible basic units in a child's linguistic system is a hazardous pastime; yet if we are to understand the processes of language development or language behavior in general, we must make the effort to do so, since it is manifestly impossible to deal with the child's language in one large undifferentiated mass. (Ferguson, 1975)