The purpose of this module is for students to explore exponential growth and decay in relation to population modeling. Students do investigations that allow them to visualize exponential growth and decay of a population. They quickly realize that the growth/decay is not linear. The activities are good to use even if the focus is not on population modeling. Worksheets, homework, and a quiz (with keys for the homework and quiz) are included on this site. The lesson is designed to take one 90-minute period. If teachers have time and access to the internet and Excel, an extension is included for a 2-3 day module in which students use technology to explore population growth and decay.