摘要：Based on condition of Mathematics teaching-learning process last year, showing that few students participated in lecturing. Generally, more students just listened to lecturer’s explanation, wrote concepts and examples of problem of topics which were being discussed. So that, effective teaching-learning strategy that capable to activate the students in Mathematics course requires to be managed systematically and continually. In this paper describe the strategy which can improve the quality of Mathematics lecturing. The name of that strategy was co-operative learning. This strategy has been implemented in D3 Electrical Engineering Study Program (D3-EESP) in Engineering Faculty, State University of Yogyakarta. Subjects of the implementation the strategy were all students of D3EESP that taking Mathematics course. Efficacy indicators of this implementation were: (1) when students have participated actively in course classroom, (2) students have participated actively in finishing group duties. From those results, students would have improved their ability in comprehending course items. Result of this implementation indicated that the strategy of co-operative learning succeed to improve the attitude of students in Mathematics lecturing. This efficacy indicator could be seen from student activities in following lecturing, also cooperation of among students in finishing duties were better than before. Another indicator was the increasing amount of students who dare to enquire in class at the time of lecturing take place. Besides, if it was seen from score of Mathematics course, there were 19 out of 34 students had score 60 or more that classified in enough good category (C+) to very good category (A). In another word, there were 55.9% of all students have had passed from Mathematics course. It was a good result
