Feasibility and Preliminary Vocabulary Learning Outcomes of a Thematic Digital Visual Dictionary for Mandailing, Indonesian Based on Local Wisdom

Abstract

Indonesia's reading literacy performance, as reported in the OECD's PISA 2022 results, remains below the OECD average, and limited vocabulary mastery among students in bilingual communities such as the Batak Mandailing is often cited as a contributing factor. At the same time, everyday use of the Mandailing language among younger community members appears to be declining. This study reports the development, expert validation, and a preliminary single group trial of a Thematic Digital Visual Dictionary for Mandailing, Indonesian based on local wisdom, developed as a vocabulary learning medium for elementary school students using the Research and Development (R&D) approach with the ADDIE model (Analysis, Design, Development, Implementation, Evaluation). The product was reviewed by three experts, one material expert, one media expert, and one language expert, who rated it Highly Feasible, with a combined mean validation score of 3.51 on a 4 point scale. In a one group, one session pretest, posttest trial conducted 1 to 5 July 2026, all 25 students of the Grade 5 class (15 female, 10 male; age 10 to 11 years) at SD UPTD 04 Simatahari (population 156) completed a Mandailing thematic vocabulary test immediately before and after an approximately 60 minute period of independent product use, then completed a user response questionnaire. Users rated the product positively for practicality and usefulness (mean = 3.48, Highly Feasible category). Mean thematic vocabulary scores rose from 54.12 (pretest) to 79.40 (posttest), with an average Normalized Gain (N Gain) of 0.56 (moderate category; Hake, 1998). Because the design used a single group, one immediate posttest, and no comparison condition, these results are best read as preliminary evidence of product feasibility and a short term thematic vocabulary gain, not as evidence of broader language literacy improvement or language revitalization; controlled and longer term studies are needed before such claims can be supported.