Allan Glatthorn described nine types of curriculum operating in schools: the recommended curriculum, written curriculum, taught curriculum, supported curriculum, assessed curriculum, learned curriculum, unintended curriculum, evolving curriculum, and flexible curriculum. These include curriculums that are recommended by experts, intended for control, delivered in classrooms, supported by resources, assessed through tests, learned by students, and unintended. The curriculum also evolves based on community needs, provides logical subject sequences, and complements other community programs.