APPLICATION OF THE PJBL-STEM LEARNING MODEL ON SMOKELESS WASTE COMBUSTION DEVICE ON TEMPERATURE, HEAT, AND EXPANSION TO IMPROVE THE COGNITIVE LEARNING OUTCOMES OF STUDENTS OF CLASS VII SMPN 1 TAPUNG HULU. SPEKTRA [Internet]. 2026 Mar. 9 [cited 2026 May 28];11(1):186-99. Available from: https://ojs.unsiq.ac.id/index.php/spektra/article/view/8900