Lab - Exponential functions: Doubling times and growth rates

This is a lab that I have used for years to teach my students about exponential functions. It is quite large, and I usually assign it as a major project. If a student can work through the entire lab on his or her own, that student should have no problems with the unit test. I touch on applications from biology, economics, and chemistry; so that the subject doesn't seem like a dry mathematical topic.