DEVELOPMENT OF STUDENT WORKSHEET PROBLEM BASED LEARNING MODEL ORIENTED BY CRITICAL THIKING ACTIVITIES IN VIBRATION, WAVE, AND BEEF TOPIC IN CLASS VIII SMPN 3 PADANG. universe [Internet]. 17 Juni 2021 [dikutip 16 Agustus 2026];2(1):77-83. Tersedia pada: http://universe.ppj.unp.ac.id/index.php/universe/article/view/59