Few things are as amazing as watching your child's language development evolve. Simple words such as "ball" and "doggie" morph into full sentences such as, "This doggie is playing with a ball." Roger Brown (1925-1997), a professor of social psychology at Harvard University, developed what is known today as Brown's Stages of Syntactic and Morphological Development, which tracks children's language acquisition in terms of "mean length of utterance measured in morphemes." (MLUm). A morpheme is a unit of meaning in language. For example, although the word "happy" has two syllables, it contains one morpheme; "unhappy" has two morphemes. The MLUm increases as children move through Brown's stages and acquire more language.
After children can say between 50 and 60 words and are between 15 and 30 months of age, they enter Brown's Stage I, according to Caroline Bowen, a speech-language pathologist who's an honorary professor of linguistics at Macquarie University in Sydney, Australia. Children in this stage have MLUms between 1.5 and 2.0, and can say short phrases such as "that car," "birdie go," "in bath," and "dolly bed." To encourage language development during Stage I, the American Speech-Language-Hearing Association suggests talking to your child while doing activities and going places, and finding time to read to together each day. You can also try expanding upon words your child says. For example, if she says "car," a good response might be, "You're right! That is a big red car."
During Brown's Stage II, children are between 28 and 36 months of age, and have MLUms between 2.0 and 2.5, according to Bowen. They begin using the present progressive tense (-ing verbs), and using "in" ("in box") and "on" ("on box"), and also -s plurals ("my cars"). To facilitate language growth during Stage II, ASHA recommends using clear, simple speech that is easy to imitate, and showing your child you're interested in what he has to say by continuing the conversation. For example, if your child says, "pretty flower," follow up with "Yes, that is a pretty flower. The flower is bright red. It smells good too. Does Sam want to smell the flower?" It's also helpful to discuss synonyms for familiar words while reading together (i.e., mommy, lady, grown-up).
Children in Brown's Stage III are between 36 and 42 months of age, and have MLUms between 2.5 and 3.0, according to Bowen. They begin using the irregular past tense ("me fell down") and 's possessive ("Dada's book"). They also start using copulas, which are words that link a subject and predicate ("I am tall"). ASHA suggests you can help a child in Brown's Stage III by sorting items or pictures and talking about which don't belong and why (i.e., a baby does not belong with a dog, cat and mouse). Reading, talking, singing and rhyming about what you're doing and where you're going also is valuable. Also, have your child retell a story you just read or act it out using props.
In Brown's Stage IV, children are between 40 and 46 months of age, and display MLUms between 3.0 and 3.7, according to Bowen. It's at this stage they begin to use articles ("a book," "the ball") as well as the regular past tense ("she jumped"). Children also start using the third person regular tense ("puppy brings it"), as well as the present tense. To stimulate language in Stage IV, ASHA suggests looking at family pictures with your child and asking her to explain what's happening in each one. Another good language-boosting activity for this age is to cut out pictures together from magazines and arrange them in unexpected ways. For example, glue a dog inside a car as if the dog is driving. Ask your child to explain what is silly about the picture.
In Brown's final stage, children are between 42 and 52 months of age and have MLUms between 3.7 and 4.5, observes Bowen. In Stage V, they begin using the third person irregular ("he does, "she has"), uncontractible auxiliaries ("are they swimming?"), and contractible copulas ("she's ready," "they're here"). To foster the flow of language in this stage, ASHA recommends giving your child your undivided attention when she's speaking and to acknowledge and praise her afterward. They also recommend encouraging social communication and narration skills by role-playing using props and dress-up clothes.