Below are a set of short videos that introduce ideas about maximization of a function of a single variable that are related to economics. The approach is the one I'd take in teaching a Math for Economists class. Content-wise, this is pretty much the same as what I would have done 20 years ago on a blackboard, except that I'm a bit more sparing with all the derivations. Here is a PDF of the finished writings. (It needs to be rotated counter-clockwise to be viewed online.) I wonder how useful students would find that, if that had these videos as well. There is nothing novel about this approach except the captions, which can translate into many different languages, and the image quality, which seems to me exceptionally clear, at least relative to what could be done just a year ago.