"Commodity Prices" is a great app to teach your students about Ag Business. It will help you track the market and see how prices rise and fall. You could even do a project where you have students track something like corn prices for a whole semester.
How it works: It has a simple and clean interface that lets you go in and select many things that are in todays market. When you select something say the price of hogs, it will take you in and show you all the information about the recent rise and fall of the hog market. It will even give you videos to watch and news articles to read.
https://itunes.apple.com/us/app/commodity-prices/id619438696?mt=8