When do children start to use “dialogue for learning” in a school context?

I’ve been cleaning out my collection of text books and was prompted to see how many of my books on language–language and development, language and learning, language and literacy, language and school success–were outdated.

With my interest in dialogue and its relationship to school success, I stopped to skim several old texts that still seem relevant to me. Here are some examples:

The Language of Learning: The Preschool Years by Marion Blank, Susan A. Rose and Laura J. Berlin, Grune and Stratton Publishers, 1978

“Regardless of differences in orientation (toward teaching thinking in the preschool), one factor that almost all programs share (with the notable exception of Montessori) is the importance placed on the verbal exchange that occurs between the teacher and the child.” (p.3)…

Talk for Teaching and Learning, Joan Tough, Ward Lock Educational (from Britain), 1979

“The project was first established under the title Schools Council Communication Skills in Early Childhood Project. During the development stage many teachers (of the 1000 who participated) felt that teachers who worked with older children should also be aware of the part that talk should play in children’s learning and in teaching.” (p. v)

Does talk, dialogue, language still play an important role in learning? Only for preschoolers?

Consider some contemporary sources:
Speaking and Listening for Preschool Through Third Grade, Lauren Resnick and Catherine Snow, International Reading Association, 2008

“Speaking and listening are the foundations of reading and writing. A child who does not have a large and fluent vocabulary will have difficulty with every aspect of reading, from recognizing or sounding out words to making sense of the story or set of directions. A child who can’t tell a story orally will have trouble writing one. Parents and educators know this instinctively,but they have had few resources to rely on in determining what speaking and listening abilities they should expect from children at different ages.”

Comprehension Through Conversation, Maria Nichols, Heinemann, 2006

“..Allington’s assertion that conversational talk was still under researched was the impetus I needed to begin broadening my own focus on talk.” (p. vii)

Academic Conversations: Classroom Talk That Fosters Critical Thinking and Content Understanding, Jeff Zwiers and Maria Crawford

“I didn’t know what I knew until I talked about it.” Seventh-grade science student.

What do educators know about the speaking and listening abilities students need to succeed in school? How do we teach those speaking and listening skills? What role does teacher modeling play? Are there specific contexts, resources, approaches that will help children develop these communication/dialogue/language skills? When should we begin? When should we stop teaching/learning about language, communication, dialogue skills?