<![CDATA[Purpose – Object-Oriented Programming (OOP) is challenging for students because its abstract concepts are difficult to translate into practical programming solutions. This study developed OOPify, a visual block-based learning environment for OOP practical activities, and examined changes in students’ conceptual understanding and group-level practical performance.Methods – The study employed a Research and Development approach using the ADDIE model and a one-group pretest–posttest design. Participants were 34 vocational high school students in West Java, Indonesia. Data were collected through OOP conceptual understanding tests, group-level practical performance observations, expert validation, and student response questionnaires.Findings – OOPify was rated feasible (82.5%) by one expert. The Wilcoxon Signed-Rank Test indicated a significant improvement in OOP conceptual understanding (p < .001), with 70.59% of students achieving moderate-to-high N-Gain and an average N-Gain of 0.50. Group-level practical performance, covering psychomotor, cognitive, and collaborative indicators, averaged 85.22% across Meetings 2 and 3. However, these results represent preliminary observational evidence because formal inter-rater reliability was not assessed.Research implications – Visual block-based learning environments may support OOP learning by reducing syntactic complexity and allowing students to focus on concepts and problem-solving. Generalizability is limited by the single-school context and absence of a control group.Originality – This study integrates visual block programming, OOP practical activities, and group-level practical performance within a single learning environment.]]>
