Problem-Based Learning ~ what is it? This Edutopia article, titled Solving Real-World Issues Through Problem-Based Learning, explains how "The perfect problem connects content, student interest, and an authentic context." High school students should start with Problem-Based Learning, by selecting a "problem" of their choice...one that they are really interested in. They should then be guided through the Inquiry Process. I recommend Barbara Stripling's (of Syracuse University) Model of Inquiry. As students engage in the Inquiry Process, they develop critical thinking skills, necessary for lifelong learning. Allowing students to think critically deepens their learning experiences and ultimately leads to higher learning outcomes.
This high school OER Commons Collection, titled Problem-Based Learning, has a number of resources to get students started with Problem-Based Learning experiences.
If you have any questions, please contact me at firstname.lastname@example.org.