A central feature of every Waldorf school is the Main Lesson that occurs from 8:30–10:30 each morning. During this period, each class concentrates on one particular subject for a block of weeks. That subject is then set-aside for a time and another is taken up. This allows the class to keep a single focus in order to go deeply into a subject for a time. Alternating subjects in this way gives a healthy rhythm to the process of learning.