Implementation of the PREMIER model based on river area to improve fourth-grade students’ mathematical problem-solving ability. J. Teach. Learn. Elem. Educ. [Internet]. 2023 Feb. 18 [cited 2025 Oct. 12];6(1):27-38. Available from: https://jtlee.ejournal.unri.ac.id/index.php/JTLEE/article/view/205