The Evolution of Teaching Math
Up to the 1960's
A peasant sells a bag of potatoes for 10. His costs amount to 4/5 of his selling price. What is his profit?

In the early 1970's
A farmer sells a bag of potatoes for 10. His costs amount to 4/5 of his selling price, i.e., 8. What is his profit?

1970's (new math)
A farmer exchanges a set P of potatoes with a set M of money. The cardinality of the set M is equal to 10 and each element of M is worth 1. Draw 10 big dots representing the elements of M. The set of production cost is comprised of 2 big dots less then the set M. Represent C as a subset of M and give the answer to the question: What is the cardinality of the set of profits?

1980's
A farmer sells a bag of potatoes for 10. His production costs are 8 and his profit is 2. Underline, the word "potatoes" and discuss with our classmates.

1990's
A farmer sells a bag of potatoes for 10.00. His production costs are 0.80 of his revenue. On your calculator graph revenue versus costs. Run the "POTATO" program on your computer to determine the profit. Discuss the result with the other students in your group. Write a brief essay that analyzes how this example relates to the real world of economics.