<![CDATA[Developing elementary students' conceptual understanding of two-dimensional shapes remains a challenge because mathematics instruction continues to require learning media that provide meaningful and interactive learning experiences. This study aimed to develop an ethnomathematics-based Engklek learning medium integrated with physical Quiz Cards and digital Boom Cards using the Four-D (4D) development model and to examine changes in Grade II students' conceptual understanding of two-dimensional shapes following its implementation. The product was evaluated through expert validation, practicality questionnaires, instrument testing, and a pre-experimental one-group pretest-posttest design involving 28 Grade II students. The results showed that the learning medium met the validity criteria based on media expert (95.83%) and material expert (94.44%) evaluations and demonstrated high practicality according to teacher (83.33%) and student (89.88%) responses. An increase in students' conceptual understanding was observed following the implementation of the learning medium, as indicated by a moderate normalized gain (N-Gain = 0.50) and a very large paired-samples effect size (Cohen's d = 2.779). The developed medium integrates the physical Engklek game and printed Quiz Cards with digital Boom Cards, which provide interactive questions and learning challenges during gameplay. These findings suggest that integrating cultural, embodied, and interactive learning components may provide a meaningful learning environment for supporting students' conceptual understanding, although the one-group pretest-posttest design does not permit strong causal conclusions.]]>
