A way for teachers to counter duality in traditional patterns of thinking, especially in social studies classrooms, is to plan a lesson involving conflicting sources. In this article, the author discusses a mapping lesson for high school and college students, which helps students understand dualities. From this lesson, the student recognizes the significance of the ever-present Mercator map and that using the Peters map can change one's views of the world. When assessing the results of this lesson, those calling for higher standards, greater assessments, and better test scores should note that the students were more consistently accurate in their comparison of land masses when they used both the Peters and Mercator maps than when they used only one.