Modern classrooms are often comprised of a heterogeneous student population with varying abilities. To address this variance, third-grade teachers implemented researcher-designed, pre-differentiated, and enriched math curricula in algebra, geometry and measurement, and graphing and data analysis. The goal of the curricula was to provide academic rigor for all students, including students with high abilities. These units prompted educators to recognize learning differences in their classrooms and provide appropriate lessons for each group. Qualitative analyses revealed the treatment teachers' successful use of preassessments and grouping practices to accommodate students in their academically diverse classrooms. This study demonstrated the value of pre-differentiated and enriched curricula and professional development. Treatment teachers discussed how important it was that the curricula provided preassessments for each unit, and most lessons provided tiered activities directly connected to students' preassessment performance. Providing teachers with more meaningful and cohesive tiered activities will support teachers' efforts in academically challenging students of all levels.