Courses in clinical epidemiology usually include acquainting students with a single 2X2 table. All diagnostic test characteristics are explained using this table. This pedagogic approach may be misleading. A new didactic approach is hereby proposed, using two tables, each with specific analogous notations (uppercase and lowercase) and derived equations. This approach makes it easier to discuss the use of Bayes' Theorem and the two stages of analyses, i.e., using sensitivity to calculate predictive values. Two different types of false negative rates and false positive rates are discussed. (Contains 5 tables.)