The Atlanta Fed has an excellent lesson plan here.
The plan uses an auction and a fixed market basket of goods. Students are given play money to buy the goods. Then the money supply is increased. The teacher calculates the inflation rate using a price index. On this site, you will also find an outstanding lesson "Benjamin Franklin and the Birth of a Paper Money Economy."
If you are looking for resources that will help you teach macroeconomics, this site will help you prepare our students for the future.
About the Author: Mike Fladien is a high school Economics and Law teacher in Muscatine, Iowa. He has been called the EconHacker because he has a talent for explaining Economics concepts in a simple language that anyone can understand.