The learner-centered paradigm of education requires very different roles for technology, as well as for teachers and students, compared with the teacher-centered paradigm. Rather than almost exclusively serving the teacher for teaching, technology primarily serves the student for learning. It does so through four major roles: (1) keeping records of what each student has mastered, what is within reach to work on next, and what characteristics each student has that should influence instruction; (2) helping to create each student's personal learning plan; (3) providing an immersive, authentic project environment with just-in-time instructional support; and (4) formatively and summatively assessing mastery of each student's learning goals. Secondary roles and system architecture are also described.