This is one of my favorite diagrams ever!
Via an e-mail some years ago...
Teaching Math In 1950:
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 1960:
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 1970:
A logger sells a truckload of lumber for $100. His cost of production is $80. Did he make a profit?
Teaching Math In 1980:
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 2010:
A logger cuts down some beautiful forest trees 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. How do you feel about this way of making a living?