Big Data can radically transform education by enabling personalized learning, deep student modeling, and true longitudinal studies that compare changes across classrooms, regions, and years. With these promises, however, come risks to individual privacy and educational validity, along with deep policy and ethical issues. Education is largely a public service targeted primarily at minors. Participation is compulsory in most advanced societies, and in many ways, it is seen as a fundamental right. Academic success is necessary for advancement, but students often have little individual say in the process. For these reasons, it poses unique policy challenges that do not arise in other domains. Big data requires deep and constant monitoring of students, classes, and instructors. Who consents to such monitoring, and how will student or instructor privacy be preserved? Data also has immense commercial value. Who owns it? And who is permitted to profit from its use? In this article, I will discuss some of these unique issues, and I will outline some potential approaches that may be taken to address them.