We discussed the question, "What is the *fundamental* difference between *x*^{3} and *x*^{2}?" We decided that in speaking about how they changed differently, we really needed to talk about their respective rates of change. For example, *x*^{3} changes *more slowly* than *x*^{2} between 0 and 2/3, and it changes *more rapidly* than *x*^{2} for *x *> 2/3. We devised a method for estimating rates of change of a function with the function *g*(*x*) = (*f*(*x+*h) - *f*(*x*))/h, where h is a parameter.