Although we have a few models that have been able to personalize learning and do a better job of instituting mastery-based learningfor students, no one has figured out how to do it at scale per se yet, and there is still plenty of room for growth in student outcomes.
Indeed, Common Core and competency-based learning should be a natural fit, as the former creates learning maps for students to master that can shift the emphasis from time to mastery of deeper learning.