In India, the language of the instructions for most of the higher education courses (10+2 and after) is English. How much role does the language plays in making the learning meaningful is an important study. I am sure there is a deep research on this already, but here are my three cents.
Any learning based activity involves some steps such as, building context about what is going to be learned, introduction to the learning material, effort to understand learning material, be able to comprehend learning material, ability to recall learning material and relate it to the live experiences around, mastery of learned material, production of knowledge based on already learned material. Now, one can divide various stages of education that one goes through based on these different steps and call it primary, secondary, higher, college, Masters, PhD etc etc.
What role does Language plays in learning. A study of early scientists from European countries suggests that most of them studied different languages early on in their initial years. Most of them mastered many languages before they started working on their scientific output. Many of them were also studied abstract subjects like philosophy, theology etc. I believe this method of study was extensive in developing their brains early on, in trying to cope up with abstract ideas that higher education / research requires.
The better in language you are, better are your chances in comprehending the material under study flawlessly without ambiguity. Else, brain stays utilized in trying to comprehend what is written and exhausts itself there only. If you have a great vocabulary and command over language, brain is free to do the rest of the stuff, that is the analysis of the material which is required to produce conclusions and derive new hypothesis. So, it becomes important one has mastered the language in which instructions are being studied.
Why most of the students fail to understand the material provided to them? Because they simply do not possess language abilities to comprehend it correctly. That is followed by lack of experience to apply the knowledge being learned, to real life incidences. Teachers fail here, because they themselves do not understand how to apply the knowledge they have to their surroundings. You bet, if they knew this, they would be already doing better things that keeping themselves involved in rotted teaching methods. They do not understand importance of language of instruction in a students life.
English is still not a native language for most of the Indians. 70% of Indians stay in villages where they are never exposed to English as a language until they enter city life, where they see their city counterparts, flashing their convent educated speaking skills. Language plays its role in building confidence also, because in the early immature peer pressure related age, where the intra-competition amongst students is extreme, language barrier could segregate students and lower their confidence.
India in its recent history since colonization period, never had any knowledge production. Whatever contributions Indians did to science, maths, literature, arts, politics etc. (world class contribution which is considered classics like Chanakya's epic on economics titled "Arthshastra"), were ages before. Most of the contributions to these fields came from Europeans. Classics like Shakespears works, Euclids "Elements", Platos "Republic" etc. and similar other were all in a language so distant from the reach of common Indians that, most of them grew without any exposure to such great classics in the above fields. Indian classics themselves too were in "Sanskrit". There are hardly a few thousand (5000?) people who speak pure sanskrit in India. In such a sorry state, it is not difficult to understand why most of the Indians grew up in a sorry state of affairs without true education. Literacy and education are two different terms which can be strongly witnessed in India. Most of the Indians are literate, they need not be educated. Check the difference between education and literacy by classic philosopher
Mr. M. J.Adler.
So my point is language plays an extremely important role in development of a person. It is important because it helps us read correct books, comprehend them correctly, be accessible to other classic literatures and build a knowledgeable society that craves for learning to solve important problems. But, I doubt many understand this except a few.