2021. DEVELOPMENT OF LKPD MODEL DISCOVERY LEARNING ACTIVITY ORIENTED CRITICAL THINKING ON VIBRATION MATERIALS, WAVES, AND SOUND FOR LEARNING IPA CLASS VIII IN JUNIOR HIGH SCHOOL 13 PADANG. Universe. 2, 1 (Jun. 2021), 18–24. DOI:https://doi.org/10.24036/universe.v2i1.34.