The March of Progress

A commenter named Ivan Poland posted this joke over at Vox's a while back. I enjoyed it so much, I thought I'd share it, here:

Teaching Math In the fifties: A logger sells a truckload of lumber for $100. His cost of production is 4/5 of the price. What is his profit?

Teaching Math In the sixties: A logger sells a truckload of lumber for $100. His cost of production is 4/5 of the price, or $80. What is his profit?

Teaching Math In the seventies: A logger sells a truckload of lumber for $100. His cost of production is $80. Did he make a profit?

Teaching Math In the eighties: A logger sells a truckload of lumber for $100. His cost of production is $80 and his profit is $20 Your assignment: Underline the number 20.

Teaching Math In the nineties: A logger cuts down a beautiful forest because he is selfish and inconsiderate and cares nothing for the habitat of animals or the preservation of our woodlands. He does this so he can make a profit of $20. What do you think of this way of making a living? Topic for class participation after answering the question: How did the birds and squirrels feel as the logger cut down their homes? (There are no wrong answers.)

Teaching Math In 2007: Un ranchero vende una carretera de madera para $100. El cuesto de la produccion era $80. Cuantos tortillas se puede comprar?