Scalable and accessible professional development programs have the potential to address the opportunity gap many teachers experience. Yet many asynchronous online programs lack interaction with and timely feedback to teachers. We addressed this problem by developing a virtual, interactive program that uses intelligent tutoring systems to provide just-in-time feedback to teachers. We conducted a randomized controlled trial with teachers across the United States in which teachers were assigned to either this program or no additional training. We found that teachers who completed our program (N = 29) used mathematically richer tasks and created a more coherent, connected learning environment for students to build conceptual understandings than did teachers who were in the business-as-usual condition (N = 23).