Project-based learning (PBL) organizes learning around complex projects that involve students in design, problem-solving and investigative activities. Students work relatively autonomously over extended periods of time to produce realistic products or presentations. Defining features of PBL include authentic content and assessment, teacher facilitation, explicit goals, cooperative learning, reflection, and incorporating adult processes. PBL projects are central to the curriculum, focused on driving questions that require students to encounter and struggle with central concepts. Investigations in PBL are constructive and involve inquiry, knowledge building and resolution to transform and construct new student understandings.