When an Idaho school district initiated computerized adaptive testing, it discovered that all the growth occurring in the district was limited to the lowest-achieving students. The more proficient students, which included both gifted and above-average learners, showed little or no growth. The assessment data showed a weak curriculum that tended to focus on what students already knew and could do. The district decided to implement a concept-based curriculum, which teaches big ideas and enduring understandings. The district also shifted to leveling, or flexible grouping, and initiated a gifted and talented program for students in its elementary and middle schools. In some of these classes, 90 percent of students met their growth targets.