The instructional and assessment environments that students experience can have an enormous impact on their mathematical success, their understandings of what mathematics is, and their views of themselves as learners and doers of mathematics. While there has been ample research conducted about how teachers use assessment results to inform their instructional practices, the few studies specifically addressing the relationship between the instructional approaches and the types of assessments that teachers use have yielded inconsistent results. The aim of this dissertation was to explore this relationship and how it may be impacted by the racial composition of a class. Systemic racism and white supremacy have an enormous, yet often invisible, impact on all aspects of life in the U.S., which certainly extends to the classroom. Consequently, this dissertation used the Critical Race Theory (CRT) and QuantCrit frameworks to examine whether and how classes with different racial compositions are exposed to differing instructional and testing environments in U.S. mathematics classes. CRT provided this work with a solid theoretical justification for focusing on race and the QuantCrit extension of CRT guided my methodological decisions.