This looks to be a good resource for K-12 inquiry-based projects that focus primarily on math and science (though there are connections to social studies and language arts). It is searchable by grade and subject.
This is a great PBL unit that is designed for grades 3-5; however, it could be modified to fit upper levels as well. This project also describes how it meets the essentials elements of PBL. Very easy to follow.
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.
This is a PBL designed for Kindergarten, but could be adapted for any elementary grade. It is a great launching pad for some really authentic learning!
A great graphic that illustrates what to keep in mind as you work to implement PBL in the classroom. Created using information from PBL in the Elementary Grades - Chapter 8.