Ibrahim M, Jamaludin KA. The roles of teacher and students via blended problem-based learning: Improving students’ mastery of three representation levels of chemistry. EJSMT [Internet]. 2019 Dec. 13 [cited 2024 Nov. 24];6(2):9-21. Available from: https://ejournal.upsi.edu.my/index.php/EJSMT/article/view/2745