Introductory macroeconomics textbooks rarely cover the topic of marginal tax rates in sufficient depth to make it meaningful to students. We offer a simple method of introducing the concept of effective marginal tax rate that is interactive and will engage students to analyze the importance of including state income tax and FICA taxes. Our exercise will help students to observe the behavior of the effective marginal tax rate as income level increases. We also introduce an international component to the topic by comparing effective marginal tax rates across a group of socially diverse countries.