When I first read Dr. Montessori's book, The Secret of Childhood, I was awed by how she described the absorbent mind of the child — infant through age three. I agreed with her analysis based only on my experience as a parent and an educator's intuition.
Now, having read Chapter 6 "The Impact of the Earliest Years on Students' Success" in Clayton Christensen's Disrupting Class (see November 13 and 19 posts below), research confirms Dr. Montessori's theories and work. Essentially, the book states "[Todd Risley's and Betty Hart's] particular strand of research is teaching us that a significant portion of a person's intellectual capacity is determined in his or her first 36 months." Their research presents "extra talk" and "business talk" in "language dancing" as being instrumental in a child's language acquisition.
Further, Christensen goes on to state "There is a strong connection between what neuroscientists are learning about how the physical brain functions and the observations that extra talk, or language dancing, leads to keen auditory skills, which in turn leads to improved learning capacity."
Reading this chapter alone is worth buying the book. There is much much more that you will learn beyond this one chapter.