This study aims to develop the SERLI Application, an Android-based Natural Science learning module accessible to students and teachers anywhere. The application development model used is the Hannafin & Peck Model, which includes needs analysis, design stages, and implementation & development. The user satisfaction evaluation method used is the End User Computing Satisfaction (EUCS) method, considering variables such as content, accuracy, display format, ease of use, and timeliness. The application was tested by experts with a success rate of 86.58%, and by student and teacher users with a success rate of 85%. The implementation result is an Android-based learning application product containing a science lesson module. The application features an initial registration screen, a main display with modules and practice questions, and a teacher-specific display. The study addresses the low interest in science and mathematics among 6th-grade students at SDN 8 Mamboro, where students prefer interactive and visual learning materials. The application is designed to enhance accessibility and interactivity, supporting both in-class and out-of-class learning. The research methodology involves Research and Development (R&D), data collection through questionnaires, and literature review. The application was developed using Java and Firebase for the database. The results show that the SERLI Application is well-received and effective in supporting natural science learning, with high user satisfaction and successful functionality testing. Future improvements include expanding the content to include videos and enhancing compatibility with other operating systems.This study aims to develop the SERLI Application, an Android-based Natural Science learning module accessible to students and teachers anywhere. The application development model used is the Hannafin & Peck Model, which includes needs analysis, design stages, and implementation & development. The user satisfaction evaluation method used is the End User Computing Satisfaction (EUCS) method, considering variables such as content, accuracy, display format, ease of use, and timeliness. The application was tested by experts with a success rate of 86.58%, and by student and teacher users with a success rate of 85%. The implementation result is an Android-based learning application product containing a science lesson module. The application features an initial registration screen, a main display with modules and practice questions, and a teacher-specific display. The study addresses the low interest in science and mathematics among 6th-grade students at SDN 8 Mamboro, where students prefer interactive and visual learning materials. The application is designed to enhance accessibility and interactivity, supporting both in-class and out-of-class learning. The research methodology involves Research and Development (R&D), data collection through questionnaires, and literature review. The application was developed using Java and Firebase for the database. The results show that the SERLI Application is well-received and effective in supporting natural science learning, with high user satisfaction and successful functionality testing. Future improvements include expanding the content to include videos and enhancing compatibility with other operating systems.