This paper examines the use in microeconomics textbooks of what we call 'impossible examples', looking specifically at certain examples employed in chapters dealing with the production process or markets for factors of production. After showing that such examples are mostly to be found in textbooks for beginners, it asks what beginner students can possibly learn through them, taking the case of a concept (the marginal product), a law (the law of diminishing marginal product), and a theory (the income theory of distribution). The use of impossible examples in such textbooks appears to be a riddle, since, by using them to introduce, present, or explain parts of neoclassical theory, authors are in effect teaching a fake and inconsistent version of that theory.