The functions of listening, speaking, reading, and writing, should form a solid foundation from which students can learn as they grow toward maturity in their educational endeavors. Without a proper grasp of those functions, a language imbalance occurs. One might say that the foundation tilts because the base is not sufficiently solid in each direction. As a result one or more language functions are slighted and may not mature sufficiently or may atrophy because of disuse.
Lloyd, B. A. (1976). Reading to Write. Reading Horizons, 16 (4). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol16/iss4/8