my father's ski instructor.
When I was 14, I had the privilege of skiing with my father's former ski instructor. Our school had a ski team. That ski instructor also taught some of my father's other classes. He had retired as a teacher, but was still skiing. He joined me for a few runs, and we got to talk on the chairlift.
I asked him about my father. I wanted to know more about the strange man who sometimes occupied our house.
He said, "Well, your father was mostly a good student, but he had a habit of climbing out of the window mid-lesson."