Case in point, I never had that much interest in marriage/divorce issues but quite a few of my students would write about this every semester and when Andrew Cherlin's The Marriage-Go-Round came out, it seemed like a good time to research a few lectures on the topic. Now it's one of my favorite topics, partially because it's so timely given the current gay marriage debates, but also because marriage and divorce rates are these fascinating windows into all kinds of larger social changes, not just culturally, but also politically and economically.
Without getting too deep into the topic, the one thing I think it's important to remember about marriage in America (and something Cherlin's book does an exemplary job of documenting) is that it's an evolving institution and always has been. To try to fall back on claims of "tradition" doesn't work so well when you show how the purpose/function/perception of marriage has changed fairly rapidly through the years. How we do things now isn't how we did them in the past and it's hard to argue why they need to stay the same as we move into the future.
Likewise, I began to read up on obesity after it became, by far, the most popular paper topic students choose for themselves. I don't know if it's because the topic is in the news so often or if it just reflects some kind of zeitgeist but there's a grip of students every semester who want to write about obesity (usually related to children). Most of them do a decent job but I do find that they fixate on the same medical issues (Type 2 Diabetes gets namechecked practically every time) and a few of the economic costs but they some times overlook the moral dimensions of the obesity debate, which is really, to me, what much of this is about. The economic costs, in other words, are a red herring, allowing people to excoriate the fat but couch it in less scathingly personal terms.
Besides, the incredibly challenging thing about trying to discuss obesity as an issue is that, when it comes to causation, there's a tendency to treat it through starkly binary terms: either it's all about personal accountability ("people don't eat right") or it's all about the food industry ("it's McDonalds' fault) but attempts at suggesting some kind of middle ground get lost easily in the yelling match between these two fronts. On that note, if you didn't already read this earlier in the year, Marc Ambinder's cover story on obesity for this magazine was, I felt, really exemplary and a great primer on understanding just how damn complex the issue really is.
Teenage pregnancy, especially in the Latina community, is another common topic. Notably (and probably not surprisingly), almost all my students assume teen pregnancy rates are higher now compared to 20 years ago even though the opposite is true. Just goes to show one of the classic tenets of social problems work: perception often matters more than any objective reality to define the severity of a problem.