Perusall is a social learning platform that prepares students for class. The platform incorporates a novel e-book reader with collaborative annotation tools to ensure students learn more, come to class prepared, and are more engaged in the learning experience. It enables instructors to teach more effectively, understand student misconceptions, structure class discussion, and save time. It is based on extensive patent-pending behavioral research at Harvard University. The Perusall platform is always free for instructors to use with their own materials, or with open educational resources.