TEACHING MATH THROUGH THE DECADES
IN NORTH AMERICA
Teaching Math in the 1950's:   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 1960's:  A logger sells a truckload of lumber for
$100.  His cost of production is 4/5 of th price, or $80.          
What is his profit?

Teaching Math in the 1970's:  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" is the cost of production and contains 20 fewer pints 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 the 1980's:  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 1990's:  By cutting down beautiful forest trees,
the logger makes $20.  What do you think of this way of making  a living?
Topic for classroom discussion after answering the question: How did the
forest birds and squirrels feel as the logger cut down the trees?  There
are no wrong answers.