ecause most NSs teaching a conversation class normally spend at least a small portion of each class talking about English or other subjects, it might be said that a formal lecture series is unnecessary. However, it is the formality of a lecture that makes it effective. While some students may listen carefully and be able to benefit from such things as a teacher's description of a movie or a lengthy explanation of a particular idiom, much of this sort of input is often not comprehended by students. It may be that the teacher lacks the skills to make the input comprehensible, or that the input is too disorganized to be coherent, or even that students are not really aware that they are supposed to be comprehending. As Park (1995) notes, tests that are used for college screening put "disproportionate emphasis on the testee's ability to analyze, and translate word-for-word, a small amount of written English" (p. 254). That is, students have studied English for many years in a system where the content is discarded after "solving the problem." Such analysis and translation is far from sustained communication. It is therefore often a shock to students to learn that the goal is to grasp the meaning of what is said in class, retain it, and later put it to use in predicting the pronunciation of a given sentence.

A formal lecture, in addition to being more organized and placing better-defined demands on students than teacher talk, also offers itself more readily to reviewing, which will give further CI as well as increase retention. One effect of the lecture/exam system that can easily be overlooked is that it provides powerful motivation for a NS to work to be comprehended. (This is not necessarily be in effect for a content course taught by a professor fluent in Korean, because when communication becomes difficult, the temptation is great to switch to Korean, and this may become a habit.) At any rate, the English in a content course for adults normally has to be modified according to the level of the students.