IMPROVEMENT OF STUDENT LEARNING ACTIVITY AND LEARNING OUTCOMES BY USING PROBLEM-BASED LEARNING MODEL ON HUMAN REPRODUCTIVE SYSTEM TOPIC IN GRADE XI IPA 4 AT SMAN 2 SOPOSURUNG BALIGE. JPP [Internet]. 2016 Sep. 1 [cited 2026 Mar. 23];4(3). Available from: https://jurnal.unimed.ac.id/2012/index.php/pelita/article/view/6618