The main aim of this study is to integrate cooperative learning strategies, mastery learning and interactive multimedia to improve students' performance in Mathematics, specifically in the topic of matrices. It involved a quasi-experimental design with gain scores and time-on-task as dependent variables. The independent variables were three instructional strategies (CCL, CML and CCML) with academic abilities as the moderator variable. The sample for the study was 262 Form Four Malaysian students. A courseware entitled "Matrices" was developed using Macromedia Authorware as the authoring tool. In this study, the collected data was used to investigate the effects of the three learning strategies on the gain scores and time-on-task. Based on the gain scores and time-on-task, the effectiveness of the three learning strategies was discussed. This study showed that the CCML and CML strategies were superior compared to the CCL strategy; CCML strategy produced the highest gain score. For students with low academic ability, the CML strategy was found to be the most effective strategy. The findings of this study also suggested that high academic ability students would obtain high gain scores regardless of the instructional strategies. In terms of time-on-task, students in CCL and CML strategies demonstrated significant lower time-on-task than CCML strategy. (Contains 10 tables and 1 figure.)