It’s important for students to know a bit about barter. After all, barter was the beginning of trade and the source from which all modern commerce springs. Barter has mainly fallen out of use today because it is an inefficient economic system. Why is it inefficient? This fun activity from Lesson 2 of The 21st Century Student’s Guide to Financial Literacy brings home the realities of the barter system. In this lesson, students are trying to find a double coincidence of wants — which is a requirement for a successful barter.