One of the most difficult concepts for students to grasp in accounting courses is this - "How can we possibly make more money by accepting a new additional order for a selling price below our total standard cost!?!? How is that possible? Why is it absolutely essential that we properly understand and classify costs into their FIXED and VARIABLE components? Why is it important that we clearly understand the concepts of and accurately measure the "Marginal Revenue", "Marginal Cost", and the "Marginal Contribution" from an order?