Yamansabeedin, Narisara, Songchai Ugsonkid, and Chanisvara Lertamornpong. 2026. “The Effects of Discovery-Based Mathematics Instruction Using Circular Paper Folding Activities Focus on Grade 9 Students’ Problem-Solving Ability on Circles”. Interdisciplinary Academic and Research Journal 6 (2). Maha Sara Kham, TH.:e290230. https://doi.org/10.60027/iarj.2026.e290230.