As a professional, your employer is entitled to pay you a yearly salary. In such case, you are paid the same weekly amount whether you work 3 hours a day or 13. If the school chooses to pay you by the hour, then they can only pay you for 3 hours if that's how long you work. BUT they have to pay you for 13 hours if that's how long you work. PLUS, you are entitled to 1 and 1/2 your hourly rate for every hour over 40 you work in any one week.