Yes, i don't know that dividing an annual salary by 9 months is really a fair way to determine what their hourly pay is.
If you divide their pay by the number of hours worked, why isn't that fair?
Why? Many teachers work those other 3 months. I certainly dont get 3.5 months of vacation counting holidays. I'd consider that a huge pay increase if I got that.
But that is how long their contract is for. If the teacher wishes to go to school for self improvement, that is also paid for them.