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 2025, 7, 143-155.