<![CDATA[This study aims to develop a Discovery Learning-based Student Worksheet (LKPD) using Geoboard on the topic of plane figures area to improve cognitive learning outcomes of fifth-grade elementary school students. This research employed the ADDIE development model (Analysis, Design, Development, Implementation, and Evaluation). Research subjects consisted of 12 students and 1 teacher in the limited trial class, 28 students and 1 teacher in the control class, 28 students and 1 teacher in the experimental class, as well as 2 material validators, 2 language validators, and 2 design validators. Data were collected through interviews, questionnaires, and tests, then analyzed using qualitative and quantitative descriptive analysis. The results showed that: (1) material validity obtained an Aiken's V value of 0.85 (very valid) with inter-rater reliability of 83% (very strong); (2) language validity obtained 0.86 (very valid) with inter-rater reliability of 78% (strong); (3) design validity obtained 0.86 (very valid) with inter-rater reliability of 75% (strong); (4) user responses were very positive, with teacher response reaching 92% and student response 91%, both categorized as very good; and (5) the experimental class achieved an average N-Gain score of 0.66 (66%), categorized as effective, significantly higher than the control class which obtained 0.46 (46%), categorized as moderately effective, with a significant difference confirmed by independent sample t-test (sig. = 0.006 < 0.025). These findings indicate that the Discovery Learning-based LKPD using Geoboard is valid, practical, and effective in improving students' cognitive learning outcomes on the topic of plane figures area.]]>
