Several educators have advocated teaching thermodynamics using a"global" approach in place of the conventional "local" approach. This article uses four examples of experiments to illustrate the two formulations and the definitions of heat and work associated with them. Advantages and disadvantages of both approaches are discussed. The article concludes that either formulation can be used for conceptual understanding of the first and second laws of thermodynamics, that the local formulation is usually less complicated, and that the choice of a formulation for evaluating thermodynamic quantities from experimental measurements depends on the experiment. (Contains 3 figures.)