THE EFFECT PROBLEM BASED LEARNING ASSISTED BY QUESTION CARDS ON CRITICAL THINGKING SKILLS ON ADDITIVE AND ADDICTIVE SUBSTANCES FOR VIII GRADE STUDENTS OF SMPN 38 PADANG. universe [Internet]. 30 Juni 2024 [dikutip 13 Agustus 2026];5(1):51-7. Tersedia pada: http://universe.ppj.unp.ac.id/index.php/universe/article/view/585