Teweerum P, Sringan K, Wannupatam B. The Development of Learning Achievement and the Ability to Solve Mathematical Problems regarding fractions by Using Polya’s Problem Solving Concept with Bar Model for Grade 3 Students: The Development of Learning Achievement and the Ability to Solve Mathematical Problems regarding fractions by Using Polya’s Problem Solving Concept with Bar Model for Grade 3 Students. rtnb [internet]. 2025 Dec. 31 [cited 2026 Sep. 30];7(3):143-55. available from: https://so07.tci-thaijo.org/index.php/rtnb/article/view/8878