KLEUNTHAISONG, T.; KEERATICHAMROEN , W. A Study of Concepts on Ratio Matter Learning Unit and Problem-Solving Ability Using Concrete-Pictorial-Abstract Approach of Grade 7 Student. Ratchaphruek Journal, [S. l.], v. 21, n. 3, p. 93–107, 2023. DOI: 10.14456/rpjnrru.2023.37. Disponível em: https://so05.tci-thaijo.org/index.php/Ratchaphruekjournal/article/view/266840. Acesso em: 26 aug. 2026.