Ethics courses that leave students with a bunch of “you shoulds” or “you should nots” are not effective. There are deeper questions that proceed from our understanding of what human nature is about and what we see as the purpose of our life together.This is true as far as it goes, but the reason teaching such rules is not effective is that focusing on the rules fails to address the metaethical question of why we should follow any of those rules in the first place. What answer can be given to the question why one should not just be selfish, or adopt a might-makes-right ethic? If there's no ultimate accountability and we all die in the end, what does it matter how we live in this life? At bottom secular philosophy has no convincing answers. Philosophers simply utter platitudes like "we wouldn't want others to treat us selfishly, so we shouldn't treat them selfishly," which, of course, is completely unhelpful unless one is talking to children.
The reply is unhelpful when aimed at adult students because students will discern that the reply simply asserts that we shouldn't be selfish because it's selfish to be selfish. The question, though, is why, exactly, is it wrong to do to others something we wouldn't done to us? What is it about selfishness that makes selfishness wrong?
Moreover, this sort of answer simply glosses over the problem of what it means to say that something is in fact "wrong" in the first place. Does "wrong" merely mean something one shouldn't do? If so, we might ask why one shouldn't do it, which likely elicits the reply that one shouldn't do it because it's wrong. The circularity of this is obvious.
The only way to break out of the circle, the only way we can make sense of propositions like "X is wrong," is to posit the existence of a transcendent moral authority, a personal being, who serves as the objective foundation for all our moral judgments and who holds us accountable for how we live. If there is no such being then neither are there any objective moral values or duties to which we must, or even should, adhere. This lack of any real meaning to the word "wrong" is a major consequence of the secularization of our culture, it makes teaching ethics from a solely secular perspective an exercise in futility, and it's one of the major themes of my novel In the Absence of God (see link at the top of this page) which I heartily recommend to readers of Viewpoint.