How do you know if a teacher is doing their job?

My son was doing his homework and he had to write sentences for his vocabulary words, as he does everyday for homework.One of the words was Teacher. He wrote down, "My teacher never checks my homework."Needless to say, she did not check this sheet of work or I am certain that I would have gotten a call or a visit from her as some parents do for other things. My son wrote this for the very reason that his teacher does not check homework, plus he feels there is no point in doing his homework since she does not check it and there are no consequences for not doing it. Unlike me from when I was a young student, my son has not missed a day of school in his life for illness, laziness on the parents’ part, or just to have a mental day off. He has always been considered a “Star Student” a “Leader” with everything he does; Cub Scouts, Soccer in the spring, fall, and soon travel and visiting his father every Tuesday and every other weekend, along with wanting to start his own band. I work with this teacher in question at times when helping her students out. I tell him to keep doing his best and everything will be okay. A great student begins with the parents and the school working together in molding the child for success. I am now trying to find a way to talk to his teacher regarding this paper without telling her how to do her job and putting myself or my son out to be targets of me losing one of my jobs and Aaron being a good student turned to “Pick on me now” target. I have months of sheets of homework that has yet to be checked. What is a parent to do? I have talked to a few parents from my sons’ class and it turns out that they too are questioning her acts. With no leading in any part, for I am not trying to put myself out there to be a target, though I am now, I recall that homework does not go pass spelling and reading, there is no math nor history or science that comes home as I do see with the other classes in my sons’ grade. Again, I ask, what is a parent to do?