The exploration of proportional relationships is foundational to the mathematics studied in the middle grades and beyond. Research has shown that an early emphasis on procedures often leaves students with a shallow understanding of the important underlying mathematical concepts of proportional relationships. One approach that addresses the needs of both teachers and students when it comes to mathematics that middle grades students find challenging (e.g., ratios and proportions) is a unified curricular activity system (i.e., a system of curricular materials, technology, and teacher professional development). The mixed-method study presented in this article outlines a curricular activity system that was designed to underpin middle grades mathematics teachers' implementation of a learning module addressing proportional relationships. The results of the study provide evidence that a curricular activity system in which teacher professional development is coherently aligned to technology-embedded curriculum impacts teachers' ability to teach as well as students' learning of proportional relationships.