Young children thrive in classrooms that allow them to explore and discover their environment and interests and also support them in this learning. Because children learn best when they are interested and excited, early-childhood educators should offer children play-based, integrated mathematical experiences (NRC 2009). In this article, the authors describe a meaningful project-based learning experience that intrinsically invites problem solving and mathematical thinking in a preschool classroom. Project-based learning is a learner-driven approach to teaching in which children investigate significant, real-world ideas or problems. Early-childhood, project-based learning allows children to learn through exploring their world of play and further investigate their curiosities and interests.