This study investigates the development and application processes of the Computer-Assisted Digital Musical Teaching Material (Co-DiTeachMaterial) designed for easy and enjoyable musical learning of mentally retarded children. Co-DiTeachMaterial-assisted learning for the basic elements of music and recognizing various animated visuals through sounds are important for the development of auditory and visual perception of these children. Experimental study were carried out in special education and rehabilitation center with six children ranging from 7 to 11. Four modules, are created by researcher, were applied one-to-one to students. Special education teachers were asked to report their opinions. According to both the analysis reports and observation surveys, the children were more successful in the tests of Musical Instruments module than other modules of the material. Results demonstrate that lowest success rate in the Speed module was yielded and a consistent success in the modules of Sound and Environmental Sounds was shown.