Cooperative learning is an approach that develops unity and cooperation and improves the classroom activities in organized academic and social experiences. The purpose of this study was to determine the effectiveness of cooperative learning as an approach to teaching mathematics. This quasi-experimental study involved the BSCS I-A and 1B students, the first section assigned to the experimental group (cooperative learning) and the second section assigned to the control group (lecture-discussion). The study started with the administration of pre-achievement and pre-attitude tests and ended with the administration of post-achievement and post-attitude tests. The instruments used to gather data were the achievement test and standardized attitude inventory test. The scores were compared and the mean difference was determined using t-test. Findings reveal that cooperative learning improved students’ achievement in mathematics. Those exposed to cooperative learning performed better than those exposed to lecture-discussion. Moreover, cooperative learning positively influenced students’ attitude towards mathematics. Therefore, cooperative learning should be used so as to develop a more enjoyable learning environment for both students and teacher.