Ibrahim, Mokhzani, and Khairul Azhar Jamaludin. 2019. “The Roles of Teacher and Students via Blended Problem-Based Learning: Improving students’ Mastery of Three Representation Levels of Chemistry”. EDUCATUM Journal of Science, Mathematics and Technology 6 (2): 9-21. https://doi.org/10.37134/ejsmt.vol6.2.2.2019.