World Grain Supply and Demand
Before handing out this activity email the excel spreadsheet below to the students. This is a very open question to just see what they can come up with - there is really almost no wrong answer here but there will obviously be answers that use the data better than others. This can be used as an introduction to Desmos (https://www.desmos.com/calculator) where the students can enter the data from excel by copying and pasting. The Desmos graphing calculator is very user-friendly and students don't need much help to start using it usually. An example of a graph of the world grain production data is provided below in Desmos.
For more help with fitting models in Desmos: https://support.desmos.com/hc/en-us/articles/202532159-Regressions
However most of the time we help students develop their own models and we do not use the regression aspect of Desmos. Instead, we have them graph the model they come up with and check it against the data and improve accordingly.