I had a friend who retired at semester. The district paid his regular December paycheck, plus an additional amount that was roughly half of what he would have been paid over the summer. That brought his total pay for the school year to exactly half of his contracted salary, as he had worked half of his contracted days for the year. It was a nice unexpected bonus.
Another friend did the same, got his December paycheck and a "happy retirement" cake in the staff lounge at lunch.
TL,DR - call your HR office if you really want to know.