Early in every semester, I like to engage the class in a "real life" example of some type of economic phenomenon. Too often, instructors jump in with the dull routine of supply vs. demand, and efficiency vs. equity. Instead, I like to grab a few students, make them engulf 10 Swiss Cake Rolls (voluntarily of course), and then ask them how they feel. Luckily for the class, that concept won't be taught for a few weeks, but it at least gets them excited about economics.
For those unfamiliar with diminishing returns, as people employ additional units of inputs, their output increases at a decreasing rate. What does that have to do with Swiss Cake Rolls? Consider our hungry eaters as trying to maximize their utility (output) by consuming the delectable dessert (inputs). They were extremely happy with the first one, but the second one didn't bring them nearly as much satisfaction, nor did the subsequent desserts. On the consumer side, this is referred to as diminishing marginal utility. The video should help show the effects of diminishing returns. Thankfully no one had negative returns:
