Swedish doctor Hans Rosling loads a washing machine with laundry on stage at the beginning of his TED talk. When his talk is over, he returns to the washer and pulls out … books.

His presentation, "The Magic Washing Machine," is about how this one example of consumer technology is far more than a convenience. By mechanizing the arduous process of doing the household laundry, the washing machine gave women back all of the many hours they spent washing, agitating, and wringing out clothes by hand.

With a machine to do the wash, Rosling's mother had time to read to him and to learn English. That's what the books he pulled out represented: the age-old opportunity cost of doing laundry the old-fashioned way.