Pretty much what was posted just before this. Humiliation is NOT a source of encouragement. 98.9% of the time, it will bite you where you sit if you use it. I had a teacher to that do me. She earned my undying hatred. I still hate her. Instead of explaining what I was doing wrong and showing me or helping me do it right, she chose that method. I have no kind words to say for her and I think anyone who actually liked her is a fool. She was mean and totally useless as a teacher. I know. I've been a teacher also.
Shame can be a healthy thing when used properly. Shame based behaviors have to be large taboos. Such as sleeping with your sister, killing a pet, hurting a child for enjoyment, stealing from others and depriving them of a source of life that the item you took can bring. These are shameful acts. They are designed to prevent something that has far reaching consequences. When you employ shame or humiliation as encouragement whatever your justification you run the major risk of making the person Shameless. That means nothing shames them. They become immune to the consequences.
It is like Nagging. Nagging works IF and only if you use it very sparingly and when the desired results are obtained you shut up and do not bring up the subject again. If you keep on nagging, be it about the same subject or something else, Nagging stops working. I mean if you are going to nag no matter what I do why should I bother? I might as well do what I want because no matter what I do, the consequences are the same. The same goes for Humiliation. Use it even more sparingly than Nagging and only for grievous sins.
Not doing your homework is NOT a grievous sin. You make them shameless enough and they start bringing automatic weapons into a school.