Assessment and testing have become accepted practices in US schools today, to the point where teachers, parents, and students consider it excessive at the expense of instructional time in the classroom. Formative assessment programs have been implemented to improve academic performance for well over a decade. The problem that was examined by this qualitative, multi-case study was that benchmark assessment (BMA) implementation failed to produce consistent improved student performance on state assessments. The purpose of this study was to gain understanding of teachers' uses of benchmark assessment (BMA) data and how they evaluate the effectiveness of the instructional choices they make in response to those data. Purposive sampling included six 7th grade math teachers in rural Alabama middle schools. Research Question 1 asked about teachers' perceptions of their engagement with BMA data. Research Question 2 asked about their reflection and sensemaking practices, and Research Question 3 asked how teachers evaluate their instructional strategy choices. The participants' responses were coded and analyzed through the lens of sensemaking theory and data-driven decision-making, resource choices, and gauging effectiveness of instructional strategies. The constant comparison analysis yielded five themes: data usefulness, data practices, decision-making, resource choices, and gauging effectiveness of instructional strategies. The study's findings extend current knowledge regarding understanding of teachers' reflection on data engagement and teaching strategies. Researchers and educators may use the findings to both to improve teaching practice and to expand understanding of decision-making and professional development needs in data analysis and pedagogy. More research is needed to investigate teachers' perceptions of assessment purposes and alignment to teaching standards following changes in US policy affecting testing. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]