This study was aimed to investigate the effectiveness of augmented reality and modeling-based teaching in the "Solar System and Eclipses" unit. The pretest-posttest quasi-experimental design model was used in this study. For three weeks, the "Solar System and Eclipses" unit of the Science course was taught to the experimental group using modeling-based teaching and augmented reality applications, and, in the control group, the existing science curriculum was followed. The study group consists of 22 students who were in the 6th grade in the 2020-2021 academic year in a secondary school affiliated with the Ministry of National Education. Data collection tools in this study were administered "Academic Achievement Test", "21st-Century Skills Scale", and "Augmented Reality Applications Attitude Scale". The application of augmented reality and modeling-based teaching in covering the "Solar System and Eclipses" unit was positively affected students' learning and increased their levels of success, improved the 21st-century skills and improved attitudes towards augmented reality applications. Studies on augmented reality applications and modeling-based teaching in different Science course units of different secondary school grades that will contribute positively to the literature are recommended.