Assess and analyze the impacts of high-stakes standardized testing on curriculum narrowing, classroom instructional practices, and student equity in K–12 settings. Evaluate causal mechanisms, synthesize empirical quantitative and qualitative evidence, critique common research designs and limitations, and propose evidence-based policy and instructional mitigations that preserve curricular breadth and advance equity across diverse student populations and contexts. Responses should integrate theoretical frameworks, cite representative findings, and offer actionable recommendations for educators and policymakers.