In this scenario, the student is a passive participant in the process. The information learned is impersonal. Clearly, the teacher is in control of the learning process; his or her interests dictate what and how fast the students learn.
The answer in all three cases is that rudder is used to help maintain stability in the roll. A little rudder at just the right time can help keep the nose up in a slow roll or even an aileron roll, as the plane rotates through the sideways portions of the roll when gravity is otherwise not countered.
The rudder is placed so that, should the boat make any forward movement, it will be turned into the wind, so as to prevent forward momentum building up. In a centerboard boat the centerboard will be partially raised and the tiller held down hard.