Deskripsi Kesalahan Struktur Berpikir Siswa SMP Dalam Menyelesaikan Masalah Geometri Serta Defragmentingnya: Suatu Studi Kasus

It is revealed that as a compulsory mathematic subject for junior high school students, most students are struggling to solve geometric problem. As an effort to fix this condition, this article describes mistakes of junior high school students\u27 structural thinking in solving geometric problem. Subjects\u27 mistake were assessed by Subanji\u27s (2015) theory of conceptual construction mistake and mathematical problem solving. Researcher then defragmented subjects\u27 thinking structure in order to solve problems effectively. The result shows that subjects experienced miss logical construction and construction gap. Miss logical construction occurred because students\u27 logical mistake in solving the problem, while the construction gap happened due to certain incomplete schemes in subjects\u27 problem solving thinking structure. Defragmenting was conducted by assessing mistakenly constructed scheme. Then, unconstructed scheme was revealed. When scheme had considered as sufficient, the constructed scheme were knitted into an interconnected scheme and subjects\u27 thinking structure became complete. Decomposition of incorrect structured schemes used cognitive conflict, while scheme and scheme knitting applied scaffolding