This document discusses problem-based learning (PBL), an active learning approach. It provides an overview of PBL, comparing it to traditional and project-based learning. PBL uses real-world problems as the starting point for learning and involves students working collaboratively in groups to seek solutions. The document outlines the basic 5-phase PBL process and describes a workflow model. It also lists advantages of PBL such as developing students' problem-solving skills and discusses teachers acting as facilitators. Finally, it presents 4 stages of PBL involving connecting to problems, researching contexts, imagining designs, and taking action.