Design and User Evaluation of a Mobile-Based Virtual Reality Application for English Vocabulary Learning in Elementary Students

English vocabulary mastery among elementary school students in Indonesia remains limited, particularly in recognizing everyday household objects, due to conventional teaching methods that rely on passive approaches and the lack of engaging interactive learning media. Although prior work has proposed several virtual reality (VR) applications for vocabulary learning, most stop at content visualization and have not been systematically evaluated using a psychometrically validated instrument designed for child users. This study addresses that gap by designing, developing, and evaluating a mobile-based VR application for fourth-grade students, and by examining (RQ1) the extent to which the application satisfies end-user requirements across five EUCS dimensions, (RQ2) whether the child-adapted instrument is valid and reliable when applied to primary-school respondents, and (RQ3) which dimension yields the lowest score and what design implications it reveals. The application was developed using the Multimedia Development Life Cycle (MDLC) method, with content adapted from the independent curriculum and focused on household-object vocabulary. The evaluation employed User Acceptance Testing comprising alpha testing using a black-box matrix and beta testing involving 51 fourth-grade students. User satisfaction was measured using a child-adapted End User Computing Satisfaction (EUCS) instrument across five dimensions (content, accuracy, format, ease of use, timeliness), pre-tested for validity (Pearson r ≥ 0.42, all 22 items valid) and reliability (Cronbach's α = 0.87). The results indicate high user acceptance, with an overall score of 90% (very satisfied); content was the highest-rated dimension (93%), while ease of use and timeliness were the lowest (89% each), providing clear targets for the next design iteration. The study contributes a structured development and evaluation framework for VR-based learning applications at the primary level, while explicitly limiting its claims to the practicality and media-characteristic components of educational RD; it did not measure effectiveness on actual learning outcomes, which remains a recommendation for future experimental research. Keywords: Virtual reality; English vocabulary; Elementary education; MDLC, EUCS.