Abstract
Indonesia is one of the most disaster-prone countries in the world, yet disaster education remains insufficiently accessible to students with intellectual disabilities, who may have difficulty processing abstract verbal information. This study developed, validated, and evaluated the effectiveness of Big Book Sahabat Siaga, a visual-adaptive learning medium designed to support disaster preparedness among students with intellectual disabilities. The study adopted a Research and Development approach guided by the ADDIE model (Analysis, Design, Development, Implementation, Evaluation). A need analysis was conducted through interviews and classroom observations at a SLB YKK Pacitan in Pacitan Regency. Two media experts and two content experts assessed the product’s validity. The researchers subsequently conducted one-to-one, small-group, and field trials before implementing the product with four junior-secondary-level students with intellectual disabilities who were able to read and spell, with support from one classroom teacher, at SLB YKK Pacitan and SLB Negeri Ngadirojo Pacitan. The results demonstrated that the product achieved a validity score of 84.4% from media experts and 86% from content experts. Practicality scores were 83.33% in the one-to-one trial, 61.67% in the small group trial, and 85.00% in the field trial. The lower practicality score observed during the small-group trial led to revisions to the illustration, which were implemented before the field trial. Following the implementation at SLB YKK Pacitan, students’ mean comprehension score increased from 63.46% on the pretest to 96.15% on the posttest. These findings suggest that Big Book Sahabat Siaga, which combines dominant visuals, simplified language, and numbered step-by-step illustrations, can serve as a valid, practical, and effective medium for disaster preparedness instruction among students with intellectual disabilities.