Find out why the child got a zero. Seldom do we get by in life with being ignorant about other's expectations of us. You have to define your role in life and live up to it. Otherwise you will be unemployable. Children have to learn this at school.
School is a microcosm of the adult world.
It prepares students for work. This is what parents and teachers have to talk about. When your child's teacher demands responsibility from your child, support it. She's doing you and your child a favor. One young lady, let's call her Jill, is a successful marketing agent and buyer for a large retail chain.