Several months after having completed an introductory economics course, most students are no better able to answer simple economic questions than students who never took the course. The problem seems to be that principles courses try to teach students far too much, with the result that everything goes by in a blur. The good news is that a relatively small number of basic principles do most of the heavy lifting in economics. By focusing narrowly on these principles, it is possible to teach students to master them at a fairly high level in just a single semester. The author describes a simple pedagogical device that has proven effective in this effort. It is called the "economic naturalist writing assignment," an essay in which students must pose an interesting question about something they have personally observed and then use basic economic principles to answer it in no more than 500 words. The author gives examples of questions and answers.