I think this excerpt from an article by Karen Gallas (Language Development: A Reader for Teachers) from my January 2015 post on Dialogue About Language, Literacy, and Learning is worth revisiting:

Early in the chapter, the authors note:

“Talk is an inherently social act. In classrooms, however, teachers generally corral language by defining when children talk, what they are supposed to talk about and for how long. We also have implicit rules governing how talk can be used across classroom activities, requiring students to crack these code, as it were, and develop a language kit of discourses to suit the needs of different contexts. But the school is a site of may discourses in contact including both those discourses that come from students’ cultural background—their out-of-school ways of talking, reasoning, and valuing—and the many specialized discourse that are a part of the academic domain.Math, science, social studies, art, gym, music, books studies, and writing workshops all stand as distinct discourse that children must master. But discourses, by definition are complexly situated, socially, culturally, and historically.” (p. 130) (Bold mine)

It is not clear why we consider “talking” such a natural ability. It seems there is much to learn about “talking” and how to help children develop the oral language skills necessary for school success, even as early as kindergarten. Gallas and her colleagues offer us many aspects of language development to consider: