Why didn't I think of that?

In my Economics for Teachers class, the last third of the semester is being spent with the class doing group presentations. Each group was assigned a broad topic (e.g., fiscal policy, exchange rates, etc.) and must write a lesson plan and then 'teach' the lesson to the class. As I watch the presentations, I repeatedly see the students explain things in ways that are much more complicated than they need to be, while neglecting to mention things that would make the concepts clearer for their classmates. For example, the group presenting on exchange rates yesterday explained currency appreciation and depreciation without ever pointing out that when one currency appreciates, the other currency must depreciate. Part of the problem is that the students do not, themselves, have the strongest grasp on the material but it's also that it takes time (and teaching a topic repeatedly) for teachers to learn where the points of confusion are likely to be for their students and then how to present the material in ways that help clear up that confusion.

Given how many times I have taught micro principles, I think I've got a pretty firm grasp on where the points of confusion are likely to be for my students and I hope that I now present the material in ways that clear up at least some of that confusion. But every once in a while, I see or hear something that does such a better job of explaining something that it makes me hit my head and ask, "Why didn't I think of that?" This morning was one of those times, when I saw this post on Marginal Revolution. Most econ teachers know that students are forever confusing price ceilings and price floors, especially on graphs, because the terms are counter-intuitive (i.e., price ceilings are below the equilibrium price and price floors are above it). But Alex Tabarrok makes the counter-intuition memorable with the simple statement, "Only in economics are floors above ceilings". Of course! It's good to be reminded how much I still have to learn about being a better teacher...