<![CDATA[Background: Low mathematics learning outcomes among Indonesian junior high school students remain a persistent challenge, particularly in abstract topics requiring spatial visualization. Conventional teaching methods often provide limited support for conceptual understanding, highlighting the need for innovative, technology-enhanced instructional media.Aims: This study aimed to develop and evaluate the effectiveness of Augmented Reality (AR)-based Discovery Learning media in improving mathematics learning outcomes. Methods: This study employed a Research and Development (R&D) approach using the ADDIE model combined with a quasi-experimental nonequivalent control group design. The sample consisted of 60 eighth-grade students divided into an experimental group (n = 30) and a control group (n = 30). Product validation was conducted by three experts in media, material, and instructional design. Learning outcomes were measured using a 25-item validated achievement test (KR-20 = 0.84). Data were analyzed using the Liliefors, Levene’s test, normalized gain (N-Gain), independent samples t-test, and Cohen’s d effect size.Results: Validation results showed high product quality, with ratings from the media expert (88%), material expert (90%), and instructional design expert (91%), all categorized as very valid. The experimental group achieved significantly higher posttest scores (M = 77.20, SD = 6.98) than the control group (M = 68.57, SD = 8.77), t(58) = 5.537, p < .001. The experimental group also demonstrated a higher N-Gain (g = 0.541) than the control group (g = 0.350), with a large effect size (d = 1.43).Conclusion: AR-based Discovery Learning media is valid and effective in significantly improving junior high school students’ mathematics learning outcomes.]]>
