There are lots of theories about language acquisition and what is the best way to achieve it. This post is about the three types of language
The man who first postulated this idea was E. D. Hirsh Jr. He is a controversial person in some education circles, but regardless of that, this idea makes sense to me.
There are three levels of language.
Aural Language is all the language you've ever heard. If you've heard a word often enough, it is stored there. You might not know what it means, but you know the word. This is the sort of language that starts the day we are born. We have quite a vocabulary of language that means nothing, but it is in there. The more language you hear as a child, the more language you have at your disposal as you grow.
Oral Language storage includes the language you use in every day life. Most people do not plumb the depths of their language storage for words, they use the ones that are most readily available to them. Any word that is not in your aural language storage, cannot be called upon for oral language. An example of this would be the word Octogenarian. Most adults have heard that word, it means an eighty year old person. There are probably enough words in your aural storage to be able to work out the meaning of octogenarian even if you are hearing it for the first time. The truth is, most people don't use that word in conversation, even if they know it.
Experiential Language is the synthesis of your aural and oral language. Any word that is not in your aural or oral language is not available for experiential synthesis. Experiential language is the ability to encounter a word or phrase that you know in one context that is being used in a different context and be able to figure out the meaning of the new usage. Example: Let us say a child is reading along and they encounter the sentence: The old man was bitter.
If a child has never heard the word 'bitter', then that old man is a 'biter' as far as that kid is concerned, and that is a completely different thing.
If, however, the child has encountered the word 'bitter', but only in the context of seeing an adult taste something, make a pinched face and announce the concoction is bitter, then the child knows that bitter is something that puckers your face and does not taste good. The child can make one of two conclusions. Either somebody licked the old man and discovered he did not taste good, or perhaps there is something about the old man that is akin to a puckered face and a bad taste. Only experience will help a child or any reader make the proper connections.
All of this reminds me of being in AP English one million years ago. Every week the teacher would put ten words on the board we had to spell correctly by friday. We didn't have to look up definitions because she assumed we knew the words, she was just tired of having them spelled incorrectly. One week, she put 'epitome' on the board . On friday, she read the words out for our spelling test and when she came to the word e-pit'-o-me, we were confused. We had no idea that word was on our test and we all spelled it incorrectly. it was only after she wrote it on the board did we realize we'd thought it was e-pi-tome'. Despite knowing the word epitome, we did not recognize it simply because we'd pronounced it incorrectly. We did not find the word in our aural storage and we were to snotty and full of how smart we were to look the word up if we didn't have to. If we'd been forced to define it or use it in a sentence, we would have figured it out...at least, I assume we would have!
So, three types of language. The beauty of storytelling is that it is an art form that synthesizes all of the various levels of language acquisition. It improves vocabulary by exposing children to language in conjunction with images, it improves oral language through modeling and call and response, and it models experiential language with similes, metaphors, and descriptive language. Storytelling is a treasure trove of language building and development.