We report on a randomized controlled trial of an intervention that leverages the availability of laptops for all public-school students in the state of Maine. The intervention, called "ASSISTments," provides feedback to students as they solve mathematics homework problems and automatically prepares reports for teachers about student performance on daily assignments. Teachers received training and coaching on formative assessment. Data was collected from 43 schools, 87 teachers, and 2769 7th grade students. Planned analyses describe use of the intervention, analyze the impact of the intervention on an end-of-year standardized assessment, and explore variables that may moderate or mediate impacts. Findings indicate that students in the schools assigned to use ASSISTments learned more and the impact was greater for students with lower prior mathematics achievement. Although evidence shows that teachers used the intervention to target instruction to students' needs, the mediating role of this practice was unclear. We also examined the generalizability of the findings and found generalizability to be limited due to the setting in Maine. Implications for policy, practice, and future research are discussed.