In this program, we introduce students to the concept of efficiency, which is a measure of how much useful energy you get out of something compared to the amount of energy that you put into it. We answer a bunch of questions including: How much light energy do we get out of light globes compared to the amount of electrical energy that goes into them? Hint: it’s not much; they should be called heat globes! How much kinetic energy do we get out of cars compared to the amount of chemical energy that we put into them? Hint: it’s a bit more, but not that much more! And how do our arched feet make us the long-distance running champions of the animal world? This video is the most energy-efficient way of learning everything that you need to know about energy efficiency!