This study structured instrumental ensemble classes based on LT (Learning Together) cooperative learning to improve collaboration skills in music subjects, and designed music classes using Google Chrome Music Lab's Shared Piano. This lesson design using Shared Piano was structured to emphasize the advantages of cooperation and to maximize the learning effects through instrumental ensemble class, one of the collaborative activities of the music subject by applying cooperative learning model. The design of these classes aims to highlight the advantages of cooperation through instrumental ensembles, one of the collaborative activities of music subjects, to maximize the effectiveness of learning, and to improve the problems of existing ensemble classes through ensemble classes using shared piano. The procedure of the study is as follows. First, based on prior research, the ensemble class applying cooperative learning was analyzed to identify problems and improvements. Second, the instructional procedure of LT cooperative learning was structured according to the instrumental ensemble, and details for each procedure were derived. The derived details were applied to each class procedure so that not only the learning goal but also the effect of cooperative learning could be efficiently drawn. Third, based on the structure of the instrumental ensemble class, the ensemble class instruction plan was designed in a total of three sessions. The structured ensemble class specified the basic principles of cooperative learning to be emphasized for each class so that cooperation could be made more effective. Through the class designed in this study, it will contribute to achieving the educational goal of improving collaboration ability and cultivating digital literacy by enabling effective cooperative learning in ensemble classes. In the future, we hope that there will be a follow-up study on various music activities that can inspire students' collaboration skills in music classes and instrumental ensemble classes using new technology.