In this paper, the authors discuss a portion of the design research process of developing an intelligent tutoring system (ITS) for classroom use. The goal of this ITS is to simultaneously provide automated support for student learning and generate diagnostic information for teachers that can lead directly to actionable recommendations for pedagogy and classroom practice. They developed the HALF (Helping At-risk students Learn Fractions) intervention program in response to the need for a classroom-based instructional program that integrates the potential of technology-based instruction with support for teachers and the classroom environment. The results of this study suggest that the HALF intervention program has a similar positive impact on student learning as a fully developed commercial curriculum; student learning is at least as good as in an existing, widely used curriculum. Tables and figures are appended.