Students value school success but often experience classroom norms implying that learning is easy and succeeding in school is not difficult. Applying an identity-based motivation (IBM) lens highlights three ways succeed-with-ease-not-effort norms can undermine students' grades and increase their risk of course failure. Succeed-with-ease-not-effort norms reduce the likelihood that students experience school as relevant to their future goals, experience right now as the time to get going, and difficulties as signals of schoolwork's importance, not its impossibility. To support student academic outcomes, we examine "Pathways-to-Success," a classroom-level intervention operationalizing IBM theory in a 3-cycle, 3-year development design (N = 1142 8th-graders, 87% low-income families, 64% Latinx, 20% African American). We document that "Pathways-to-Success" can be sustainable; our middle school teachers implemented and taught other teachers to implement "Pathways-to-Success." We use structural equation models to show that effects are due to the theorized process; teachers who implemented with more signal clarity supported academic success by bolstering their students' identity-based motivation. We operationalized signal clarity as a mean of five fidelity components (dosage, adherence, quality, responsiveness, receipt). Signal clarity matters; students experiencing "Pathways-to-Success" with a clearer signal have a higher identity-based motivation score. Higher identity-based motivation yields better school outcomes.