FLEXIBLE LEARNING STARTS AT KEYSTONE. The Keystone School offers flexible education programs for high school, middle school and elementary students that help each student achieve their unique dreams and goals. Whether your student wants to study full-time or just needs individual classes, we offer more than 170 courses from credit recovery to world languages and AP. Students can enroll at any time. Flexibility is the foundation of our approach. For forty years, we've been known as a leader in flexible education models, and we've learned our methods support students to build the discipline they need to succeed. Whether that's in college, a job, trade school, the military, performing arts or wherever they dream to go. The Keystone School. The foundation to your student's successful future.