this was because teng qingze not only needed to play the piano, but he also needed to express the grievance and pain that he felt when he was forced to practice.
this was a huge test of acting skills.
before the shooting started, director polk sat opposite teng qingze and explained the scene to him in detail, trying to resonate with his feelings.
..."think back carefully, the pain of being forced by your mother to play the piano when you were young, to the point where you didn't want to practice anymore, but you had to persist ... the other children were playing outside, but you were locked up at home by your mother to play the piano ... are you angry? don't you feel aggrieved?"
director polk tried so hard to describe the situation that he almost cried.
he was worried that he might have gone too far. if teng qingze felt the same way as him and the child couldn't control his emotions, he might end up crying. if that happened, the show wouldn't be able to continue.