Last week I purchased a burger at Burger King for $1.58.

The counter girl took my $ 2 and I 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 two
quarters , but she hailed the manager for help.
While he tried to explain the transaction to her, she stood there and cried.

Why do I tell you this?
Because of the evolution in teaching math since the 1950s:

1. Teaching Math In 1950s

A logger sells a truckload of lumber for $100.
His cost of production is 4/5 of the price.
What is his profit ?

2. Teaching Math In 1960s

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?

3. Teaching Math In 1970s

A logger sells a truckload of lumber for $100.
His cost of production is $80.
Did he make a profit?

4. Teaching Math In 1980s

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.

5. Teaching Math In 1990s

A logger cuts down a beautiful forest 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 of $20.
What do you think of this way of making a living?
Topic for class participation after answering the question: How did
the birds and squirrels feel as the logger cut down their homes?
(There are no wrong answers, and if you feel like crying, it's ok. )

6. Teaching Math In 2009

Un hachero vende una carretada de maderapara $100. El costo
de la producciones es $80. Cuanto dinero ha hecho?