The child wasn't right.
That's okay.
They child might not know it's okay. In that case, they should receive support.
Getting marked wrong doesn't help get rid of the fear of failure; we agree about that. Not sure why you got the impression I thought otherwise.
Many people in the thread are reacting against the lesson and grading because of how they feel, not about how the child feels. That's why how they feel matters, when discussing it in an ultimately irrelevant forum.