Last week I got a burger at Carl's Junior for $1.58. The counter girl took my
$2 and was digging for my change when I pulled 8 cents from my pocket and gave
it to her. She stood there, holding the nickel and 3 pennies, while looking at
the screen on her register.

I sensed her discomfort and tried to tell her to just give me back two quarters,
but she hailed the manager for help and while he tried to explain the
transaction to her, she stood there and cried.

Why do I tell you this? Read on...

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".

Answer this 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.

Teaching Math in 1990:

By cutting down beautiful forest trees, the logger makes $20.

What do you think of this way of making a living?

Topic for class participation after answering the question:

How did the forest birds and squirrels feel as the logger cut down the trees?

There are no wrong answers.

Teaching Math in 2000:

A logger sells a truckload of lumber for $100.

His cost of production is $120.

How does Arthur Andersen determine that his profit margin is $60?

Teaching Math in 2005:

El hachero vende un camion carga por $100.

La cuesta de produccion es.............