In this article the manifold aims and theorised benefits of Learning by Design are explored and evaluated through the practices and experiences of an early years mathematics teacher. The article examines and elaborates the ways in which this teacher took up and embraced Learning by Design as both a professional meta-language and as a design scaffold that underpinned her classroom practices. In particular it is shown how Learning by Design equipped this teacher to design learning that was engaging, effective and inclusive of the diverse needs of her learners, and how she employed the language of Learning by Design to think-through, explain and articulate her work, thereby making her practices and experiences accessible to others. The research underpinning this article was drawn from a three-year project funded by the Australian Research Council.