The increased temp of research on first language acquisition in the last half of the twentieth century attracted the attention not only of linguists of all kinds but also of educators in various language-related fields. Today the applications of research findings in first language acquisition are widespread. In language arts education, for example, teacher trainees are required to study first language acquisition, particularly acquisition after age five, in order to improve their understanding of the task of teaching language skills to native speakers. In foreign language education, most standard texts and curricula now include some introductory material in first language acquisition. The reasons for this are clear. We have all observed children acquiring their first language easily and well, yet individuals learning a second language, particularly in an educational setting, can meet with great difficulty and sometimes failure. We should therefore be able to learn something from a systematic study of that first language learning experience.
What may not be quite as obvious, though, is how the second language teacher should interpret the many facets and sometimes conflicting findings of first language research. First language acquisition starts in very early childhood, but second language acquisition can happen in childhood, early or late, as well as in adulthood. The main question, which is actual, nowadays, is - Do childhood and adulthood, and differences between them, hold some keys to language acquisition models and theories? How different levels of linguistic abilities development influences on effectiveness of language acquisition?
