Students in a beginning level undergraduate classical mechanics course engaged in collaborative inquiry through the "Windwalker Project". The aim of this project was for students to create a free-standing movable structure as a way of testing and applying their understanding of the conceptual and theoretical elements of the course. This article reports on the impact of this project-based learning environment on the students' understanding of physics and describes the instructor's actions that supported their progress. Students described the benefits and challenges of this learning environment as they related to their experiences with uncertainty, efforts to overcome obstacles through collaboration, and understanding of scientific research. The instructor was able to facilitate the groups' work while supporting them with instruction on the underlying physics principles.