Why did Elie give his father marching lessons?

From the text:

Unfortunately, Franek knew how to handle this; he knew my weak spot. My father had never served in the military and could not march in step. But here, whenever we moved from one place to another, it was in step. That presented Franek with the opportunity to torment him and, on a daily basis, to thrash him savagely.

Left, right: he punched him. Left, right: he slapped him. I decided to give my father lessons in marching in step, in keeping time. We began practicing in front of our block. I would command: "Left, right!" and my father would try.

The inmates made fun of us: "Look at the little officer, teaching the old man to march...Hey, little general, how many rations of bread does the old man give you for this?" But my father did not make sufficient progress, and the blows continued to rain on him.