The way that students use mental representations when acquiring new knowledge can be exploited more systematically in the teaching of language for special purposes (LSP). A variety of modes of representation exist, including those in the external sensory world, that are received through the different senses and individual representational systems. Each individual's unique system can be determined from his choice of words or eye movements. In addition to possessing different representational tendencies in different subjects, humans have dominant modalities for each of these problems. It is important in LSP teaching to find out the students' most widely used representational system, and the system that most favors the assimilation of concepts in the specific subject area. The role of representations in concept formation must be linked with the basic process of memory. The theory of semantic, as distinguished from episodic, memory has implications for the format of knowledge representation and its organization. The basic concepts of a language are acquired extentionally, associating linguistic symbols with events and accumulating associations with time, reinforcing concept storage. This is exemplified in the concept of derivatives in mathematics. (MSE)