DEKONSTRUKSI MISKONSEPSI DAN RESTRUKTURISASI KOGNITIF NILAI TEMPAT SISWA SD MELALUI PBL BERBANTUAN BOX NITEM

This study aims to evaluate the effectiveness of Problem-Based Learning (PBL) assisted by the Box NiTem media in improving cognitive learning outcomes regarding whole number place value concepts up to 1,000,000, as well as to deeply explore the process of misconception deconstruction and students' cognitive transitions. The research employed an Explanatory Sequential Mixed Methods Design. The quantitative phase involved 11 fifth-grade elementary students selected through total sampling, followed by a qualitative phase involving 3 purposively selected students for task-based interviews. Data were analyzed using the Wilcoxon signed-rank test, N-gain scores, and thematic analysis synthesized via a Joint Display Table. The results revealed a highly significant cognitive improvement, with the mean score surging from 34.82 to 81.18 (p=0.003), a classical N-gain of 0.74 (high category), and a very strong effect size (r=0.886). Qualitatively, the intervention proved effective in deconstructing epistemological obstacles, such as zero place-holder errors, and successfully facilitated the transition of students' cognitive schemas from concrete physical manipulation (enactive) to symbolic abstraction (symbolic). The theoretical implications of this study reinforce the relevance of Vygotsky's scaffolding and Bruner's representation concepts in reducing extraneous cognitive load. Practically, educators and schools are recommended to integrate low-cost, high-impact manipulative media like Box NiTem into mathematics teaching modules to dismantle abstract misconceptions as early as possible.