An excellent paper. You have selected and integrated an appropriate set of resources. The paper is well organized, easy to follow and well structured. I really like the quotes at the beginning of each subheading. They really set the stage for the content to follow.
I certainly don't have much to add here. Your applications section is thoughtful and right on. You have covered Vygotsky's theory well.
I have spent a considerable time thinking about Vygotsky and his
basic notion that thought and language are two sides of the same coin--that
they dynamically work together to constitute mind. Now, here is my
problem--does that mean all thought. Is language sufficient for describing
thought--it's development, origins, and functions? My problem is
that there are a number of symbolic systems that I believe promote thought--visual
systems of representation, musical systems, mathematical systems, dance,
etc., etc. Are these secondary? Are they also part of the thinking
equation? Unless you think of these systems as a language and generalize
from Vygotsky one can be stumped. Clearly, Vygotsky was talking about
spoken language systems and a little about written language systems although
in some ways he presumes spoken and written to be the same. One way
out is to substitute symbolization for language and derive all the same
notions. Another is to think that language and thought take on one
character; mathematics and thought another.