Language is an essential tool for all children. Without language, children are unable to think, communicate with others, or regulate their own behavior (Vygotsky, 1978). For children having no physical or neurological difficulties affecting their speech, as well as good hearing and adequate cognitive ability, language learning occurs steadily from birth through the elementary years. Although the most rapid period of language growth takes place from birth until about age 5, children continue to develop and refine their language skills during middle childhood and throughout adolescence, regardless of which language they are learning (Bernstein & Tiegerman-Farber, 1997).
Language learning also occurs in a predictable developmental sequence; however, the rate of learning and the time at which particular skills are acquired varies greatly from child to child. For example, most children “coo” (e.g., repeat the same sound over and over such as “ooooo”) and “babble” (e.g., string together syllables like “baba” and “dodo”), beginning to use the sounds and intonations of the language they hear around them, between birth and age 6 months. Most will say their first words in their native language somewhere between 12 and 18 months of age. During the preschool years, a