Traditionally, Optical Mineralogy is supposed to be a training course in how to use a petrographic microscope.  Geologists use pretty specialized microscopes to study rocks, so the learning curve is a little steep at first.  My predecessors used the course also to provide a little math workout for students.  In my class, however, we take the approach that there is already a plenty that needs to be learned - certainly no time for frivolous and abstract math calculations purely for math's sake.  I use my Optical Mineralogy course as a tool for teaching the whole process of field data and sample collection, to sample preparation, to petrographic study.  I think it's important to learn procedures in their context and to keep in mind the big picture.