Our BIGGEST I.O.U. Alert your students to our country's ballooning national debt! Using an easy-to-understand approach by comparing the national debt to real-world examples, this chart comes complete with economic history, comparisons, and terms. Download the free Teachable Moments™ activity packet for this poster from the "Bonus Materials" tab above. ©2016. 13 x 38 inches. Laminated to last. High and middle school.