Diagrams have been used for instructional purposes for many years and recent advancements permit the design of an idea by a wider range of diagrams for easy understanding. The study employed an experimental design to examine the effectiveness of computer-based concept maps (CBCM) on students' cognitive learning of colours. A quasi-experimental design using pre and post-tests was employed. Treatment lasted for six weeks of intensive lessons of eighty minutes per week using computer-based concept map visuals. Sixty (60) students at two secondary schools in Nigeria, were divided into conventional and experimental groups. Two null hypotheses were tested at 0.05 level of significance and the data obtained were analyzed with ANCOVA and t-test respectively. The study findings revealed that students taught using the Computer Based Concept Map strategy performed better than the other group and there was no significant difference based on gender. It was recommended that CBCM should be used for teaching of the arts and other subjects in the school system.