Teaching ethics doesn't really make people more ethical. Rather, ethics flows from self-actualization as a responsible human being (what used to be called dignity) and self-training (whether intentional or not) in making ethically-meaningful choices. So, if you want to "teach ethics", including as it relates to open source, you could encourage folks to read the CatB series http://www.catb.org/esr/writings/cathedral-bazaar/ and point out what that might imply about the ethical implications of FLOSS. But going further than that would probably be useless.