Tweet over the weekend I mentioned that the Buck Institute for Education offers good project based learning activities. Most of what BIE offers is not free. There is some good free content on BIE. The most notable of that free content being their rubrics for assessing critical thinking skills, collaboration, presentation, and creativity and innovation in project based learning assignments. The rubrics are available with or without Common Core alignment. You can download the rubrics as PDFs or Word documents.
Applications for Education
Even if you don't use BIE's rubrics exactly as they're written, the rubrics could provide a good model to get you started on crafting PBL rubrics specific to the projects your students are working on.