阅读理解 A historical change is taking place in middle-school education Teachers are being asked to answer as never before for how well they serve their students It has become as common in middle schools for students to grade teachers as for teachers to grade students In fact student ratings(评价)have become the most widely used and in many cases the only important in formation on teaching effectiveness In comparing three studies of the same 600 middle and high schools in more than thirty states it was found that the number of schools using student ratings to evaluate teachers had climbed from 29 percent to 68 percent to 86 percent No other method of evaluation got that degree of usage and other studies have found similar results． One reason that student evaluations of easy to put to wrong use If they are expected to throw meaningful light on teachers’ performance the ratings must be sured in a way that shows at least some of what we’ve learnt about them from research and from experience Research and experience have shown us for example that student ratings should never be the only basis for evaluating effectiveness There is much more to teaching than what is evaluated on student rating forms．When ratings are used we know that students should not be expected to judge whether the materials used in a course up to date or how well the teacher knows the subject matter of the course There judgments that require professional background are best left to the teacher’s fellow workers On the other hand students should be asked to comment what they have learned in a course and to report in the classroom relationship with the students ability to develop interest in the subject and ways to encourage students to teach themselves | 
