# Teaching Math

## 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 exchanges a set "L" of lumber for a set "M" of money. The cardinality of set "M" is 100. Each element is worth one dollar. Make 100 dots representing the elements of the set "M." The set "C", the cost of production contains 20 fewer points than set "M."Represent the set "C" as a subset of set "M" and answer the following question: What is the cardinality of the set "P" of profits?

## 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.