upporters of Krashen's (1984) view of CI assume that if the input is comprehensible, acquisition will occur. Strictly speaking, however, this is not true. The actual requirement is that the input be comprehended. Although this does not seem to be stated explicitly anywhere in the literature, Sheen (1994) implies it when he says that "perhaps the most crucial variable controlling the success or failure in language learning [is] the individual effort of all students to apply themselves to the difficult task of learning another language.... A great deal of hard work [is required] in order to achieve success" (p. 145). Sheen notes that there is little mention of this subject in the literature. Evidently a realist, Sheen comments wryly on today's emphasis on "student needs," stating that in EFL teaching in Europe, which is quite successful, one of the needs of EFL students is to pass exams.

While we can never assure comprehension, we can increase the likelihood of comprehension. Interesting subject matter helps, of course, but the fact is, for sustained attention among language students, some form of gentle pressure on students may be required, as seen in Ohio University's foreign language program. There, language students must spend, at their convenience, a certain number of hours independently repeating tapes in lab, where they are monitored by an assistant who periodically cycles through all stations at the control panel and reports to their professors those students who, rather than playing and repeating tapes, are doing something such as reading a magazine.

A major method of maintaining student attention throughout the world of education is the test. Tests can consist of things other than formal questions, answers, and a grade. Asher's (1977) Total Physical Response (TPR) may be effective not because of a hypothetical neurological connection between body movement and language retention, but because TPR is a constant oral exam in which students demonstrate their listening skills, not by written or spoken answers, but by physical responses that are as clear-cut as the answers on a multiple choice test. This forces a student to attend carefully to what a teacher is saying. For whatever reasons, be it genuine interest or a desire for feelings of success, teacher approval, or peer acceptance, students expend effort on TPR. TPR is analogous to the following situation: a content course lecturer stops every two minutes and asks a multiple choice question. Students then punch the answer into their desktop computers, based on the information they have just received from the lecture, and a wrong answer turns on a flashing red light.

Given the extreme demands a content places on student attention, especially for lower level classes, it is unlikely that a content course will be successful without having a rigorous testing program, and a test should be given early to establish the necessity of paying attention.