PBL works has a very nice site, but they are much more interested in middle and elementary school, than high school. I like Teach Engineering. I look a PBL class this school year from a company that creates PBL units and even they are really light on chemistry and physics for upper grades.
Although this project was created using the old PBL standard the basic components of civic responsibility for second graders can be applied to professional responsibility for respiratory therapy students. The project provides a useful template from which to build my grade and content specific content for improving safety in healthcare. The projects involves: Second graders are ready to conquer the world-and they can start with their community. In Make a Difference: Civic Responsibility, elementary school students partner with local organizations to fill a real need, help a specific population, engage in public service, and make a tangible difference in their neighborhoods and beyond.
The Project Approach site has information about PBL, many examples of projects (particularly for ES) and resources to help teachers design and implement their own projects.