Perusall is a new collaborative ebook platform that keeps students on track before class. Perusall ensures students learn more, get instant answers to their questions, come to class prepared (with >90% having done the reading), and enjoy the experience. It enables instructors to teach more effectively, understand student misconceptions, structure class discussion, and save time. Perusall is free. For publishers and authors, it is the ultimate solution to IP piracy, resales, and sell-through. Perusall is based on extensive patent-pending behavioral, data analytic, and educational research at Harvard and is used by a growing number of faculty and students at different universities.