SARS-2 or COVID-19, has spread all around the world and the cases have accumulate over time, but how, and can we use math to understand and predict the trends? In this lesson students will use a computer simulation of the mathematical SIR model to understand how transmission and recovery rates affect the number of people who get infected and when. There are 2 versions/tracks. One in which students will change parameters on an interface to see how the plots change (grades 6-8/no coding experience 1-1.5 hours). The second version/track has code which students can review and manipulate to explore how to build the model for themselves (grades 9-12/coding experience 1.5-2 hours).