Began by summarizing the rules needed to compute the total derivative of a 1-form. Then gave a second example of how to compute the total derivative of a 1-form. In Lecture 13 the rules of differentiation were used to calculate the total derivative of a certain 1-form. We finished the lecture by showing how this answer is precisely what is needed for Stokes' formula to hold for a 1-form (in two variables x,y over an oriented region S in the plane). This explanation provides some justification for our rules for differentiating 1-forms.