Kholid I. The effectiveness of the Project-Based Learning (PjBL) approach in teaching mathematical modeling at the elementary school level: A systematic literature review. PSSJ [Internet]. 2026 Apr. 20 [cited 2026 Jun. 7];6(4):459-72. Available from: https://www.journal.privietlab.org/index.php/PSSJ/article/view/1341