Study after study shows evidence that ties vocabulary size to higher socioeconomic status and greater educational achievement. By age 3, children who are raised in a professional household know twice as many words as do children raised on welfare. It is not simply the number of words, but also how they are used that is important.
Vocabulary development by age 3 has been found to predict reading success and conversations before the age of 3 are directly linked to IQ development. Preschoolers who had heard more words had larger vocabularies once in kindergarten. Furthermore, when the students were in grade 3, their early language competence from the preschool years still accurately predicted their language and reading comprehension. The preschoolers who had heard more words, and subsequently had learned more words orally, were better readers. In short, early language advantage persists and manifests itself in higher levels of literacy.
There is a direct correlation between strong vocabularies and children being ready to learn to read. Many of the skills children need to get ready to learn to read are first learned in conversations. Reading aloud to children is one of the most important activities that help children get ready to learn to read. However, many of the benefits of the read aloud are lost if there is not the habit of talking to children about the story. Being read to does not automatically lead to literacy. The real link lies in the verbal interaction that takes place alongside the read aloud. Talking with children has an even stronger effect on literacy learning than reading aloud to them. Read-alouds are critical to help build vocabulary and knowledge which contributes to reading independently.
The good news is that vocabulary is inheritable—you can pass it on to your children. In our fast paced, media saturated world, thoughtful conversations are more important than ever before.