In a country like Taiwan, where Chinese is the official language, many students struggle to improve their English writing skills. The system of students' ratings of teachers at the end of each semester can provide valuable information concerning students' opinions. This paper selects 50 classes of freshmen following writing courses in a university of Taiwan from 2004 to 2006. We adopted the data envelopment analysis to identify the relative performance efficiencies of each class. This research proposed a management matrix of the selected classes' performance with 4 quadrants which could help them to know in what quadrant they are located. The results of this paper, which were expected to reveal that only a few classes are efficient, could help to provide some concrete and practical learning and teaching strategies for the classes with lower average scores.