I came across this interesting question at the Tulika Books about mother tongue.
How different are the written and spoken forms of your first language? If you want children to become familiar with their first language, which form would you look for in children’s books – formal or informal? Why?
My mother tongue is Telugu. I can read, write and of course speak the language. Yes there are differences between the written and spoken forms of the language. Written form is more formal and professional compared to the spoken form. There a lot of dialects which affect the way the language is spoken. When I was learning the language as a kid, I made an effort to learn the language that I spoke day and night. But, learning both forms of the language is equally important.
I would prefer kids books to be informal. That sparks interest in the kids and is also easier to understand. We live in the US and my son speaks Telugu at home. We read him books in English and Telugu and he loves it. These books have simple language and really simple stories (which may seem even silly to us).