Every school shall post or disseminate a daily schedule of classes showing the subjects for that day. These daily schedules shall be retained for no less than the previous six-month period. The "Board" may require, upon written notification to a school, that the daily schedules be retained for a period exceeding the previous six-month period. A proprietary school may conduct day and night courses. Career technical schools may only offer adult education with ODE approval. The "Board" shall be notified of which nights per week classes will be conducted. Clock hour students shall be scheduled to be in attendance a minimum of three hours in any one day.