Prof. Confrey was invited to present the opening plenary at the Mathematics Education Research Group of Australasia’s (MERGA) 42nd annual conference in Perth, Australia. Conference proceedings are available here. The paper reports on 3 years of design, implementation, and validation of Math-Mapper 6-8, a learning based-based DLS as a model to scale LTs. It leverages Lehrer’s (2013) notion of a “trading zone” to describe how a learning trajectory based DLS requires a system of continuous trading among learning scientists, practitioners, and psychometricians. The concept was illustrated using single case of an evolving LT whose focus is on Qualitative Graphing.