When your biology or ecology class is studying populations, show this video to explain the concept of exponential growth. You could also use it with a math class. A nice addition would be to read the children's book, The Rajah's Rice: A Mathematical Folktale from India. In the story, a grain of rice is exponentially multiplied in the same way that the narrator explains pennies would increase if the total were doubled daily. Note that he does not actually compute the numbers, so follow the video with some practice problems.