Graphing the production function F(x)=ln(x) by entering the function into a graphics calculator and copying down the result just seems like cheating.
Well, yeah. But math courses that require a graphing calculator don't ask, "write down the graph for f(x) = ln(x)".
The problem here is two-way. This professor does not understand what the graphing calculators are capable of (which he admits), nor does he understand what the previous math courses were like that relied on them.