In just two short years, an average child's speech development rockets from single-word statements like "no," to extremely complex sentences like, "Mama, may we please go to the store to get ice cream?" You've probably observed your toddler gradually acquiring an ability to speak in sentences. These usually start with two-word phrases like, "Ball up," then move toward sentences of three, four, five, and, eventually, six-word structures.
When a speech therapist evaluated my daughter at two and a half years of age, she was was impressed by my daughter's sentence length. While most two-and-a-half-year-olds speak in sentences of two to four words, mine rattled off sentences of 8, 9, or even 10 words in length. Because of this, the therapist believed that my daughter's speech was advanced in many points of communication, although she had minor delays in other areas.
Your toddler's average sentence length actually tells a lot about his stage in language development. Here are some interesting facts about the role of sentence length in a toddler's language acquisition.
1. Toddler sentence length has a clinical counterpart. In speech and language pathology, experts often use a child's mean length of utterance, or MLU, as a guideline for determining his communication abilities. An MLU is similar to a child's average sentence length, but it counts plurals, contractions, possessives, and word endings such as -ed and -ing along with actual words.
So, for example, the sentence, "I watched the bird fly away," with I, watch, -ed, the, bird, fly, and away, as separate morphemes, offers five points toward a child's MLU. Alternatively, the sentence, "Birdie fly," with birdie and fly as the only morphemes, would offer 2 points. A child's MLU, or clinical sentence length, is the average number of morphemes out of 100 spoken sentences.
2. Sentence length reflects your toddler's language skills. Your toddler's MLU and sentence length may be used to estimate his language development compared to his peers. An average 2-year-old speaks in short phrases, with an average "sentence" length of 1.91. A 2-year-old who can't speak in phrases may have a speech delay, while a 2-year-old who speaks in sentences of six words or more is undoubtedly advanced.
Your toddler's sentence length can give you a bit of insight into his stage of language acquisition. If he speaks in very long sentences compared to his peers, he's likely to also be an early reader. Short sentences don't necessarily mean that your child is delayed, but they may indicate that your child isn't particularly chatty.
3. There are broad age-related norms. You may find it interesting to compare your toddler's MLU or sentence length to the average for his age, but remember that an expert evaluation would be necessary to truly determine if he is exceptional or delayed for his age group. If you do compare your toddler's MLU to his peers, these are the accepted averages:
MLU Age (months)
4. Sentence length is sometimes a cause for concern. Sometimes, but not always, a toddler with short average sentence lengths has an underlying developmental delay. Children with autism, PDD-NOS, hearing problems, cognitive delays and neurological disorders often have difficulty forming sentences on the same timeline as their peers.
If your toddler doesn't speak in two-word phrases at least occasionally by age 2, or if she doesn't speak in three to four-word sentences by age 3, you should certainly talk to her pediatrician. Although it's possible that there is nothing "wrong," these delays in acquiring sentence length sometimes warrant treatment.
5. A toddler's sentence length doesn't mean everything. Both parents and speech-language pathologists are sometimes guilty of over-analyzing a toddler's speech patterns. So, if your toddler doesn't speak in very long sentences, it's quite likely that he simply prefers succinct communication. Sentence length alone is never used alone to diagnose a speech delay.
Consider that even adults vary tremendously in their sentence lengths. If someone asks you what you want to drink, your response might vary from, "Tea, please," to, "I would like a half-sweet, half-unsweet tea with no lemon, please." Neither of these responses is truly correct or incorrect. One satirical study even parodied the use of sentence length in language pathology, pointing out that adults' sentence lengths vary depending on the amount of coffee that they have had.
So, while your toddler's sentence length is an interesting and important facet of his language development, it is not the be-all-end-all determiner of his speech skills or intelligence.
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