Discovering a derivative

Teachers can often make up for a lack of creativity by keeping up with the literature. I never consid ered myself an imaginative or creative teacher, but I was well read; I attended lots of conferences and workshops, and I borrowed and copied whatever I could. My favorite lesson is a discovery les son in calculus, cobbled together from several sources. What makes it my favorite lesson is the number of times students have told me that this lesson has generated an "aha!" moment for them. The lesson, which extends over a couple of class periods, focuses on the derivative of exponential functions. Once students know how to use the calculator to find numerical derivatives, I ask them to do so for the function y = 2\ evaluating the derivative at