The purpose of this study is to provide an account of teacher perception of core practice tasks in data use, particularly data interpretation. Data interpretation is critical to professional practice in planning instructional adjustments for student learning. This is a case study of four elementary teachers who provide numerous task-specific examples of data use. The findings yield a 3-phase model of tasks that support data interpretation. Phase 1 (Observation) entails collecting critical skill data from various sources and "analyzing" data using familiar frameworks such as standards-based criteria for core subjects. Phase 2 (Interpretation) is comprised of three core tasks: "comparing" scores to predetermined target ranges, "contemplating" student connections to curriculum, and "integrating" student-based information if/when students fall short of achievement targets. Phase 3 (Adjustment) involves "reinforcing" student learning and "referring" students for specialized services when warranted. Variable practices in this data use model are attributed to teacher perceptions of successful or unsuccessful students. Discussion encompasses study implications, connections to existing literature, study limitations, and extended research recommendations. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]