Educationalists have had serious problems in proposing well-grounded ways of teaching critical thinking. Reviews of the field have called for research to develop theory concerning the learning experience associated with critical thinking enhancement, as well as to explore more tailored teaching and evaluation methods. This article suggests an approach to teaching critical thinking with potential to handle these concerns. Based on an analysis of students' essay responses, the article carries out a thought experiment to elaborate an example of design and enactment of lessons using the variation theory of teaching and learning. In this way, the article offers the research community a thorough description of a theory-driven and tailored tool for teaching and evaluating critical thinking, which deserves further exploration.