You can't teach mathematics without inviting Tom Lehrer. You know that, don't you?
You can't take three from two
Two is less than three
So you look at the four in the tens place
Now that's really four tens
So you make it three tens
Regroup
And you change a ten to ten ones
And you add it to the two and get twelve
And you take away three
That's nine.
Is that clear?
Now instead of four in the tens place
You've got three because you added one
That is to say ten
To the two
But you can't take seven from three
So you look in the hundreds place
From the three you then use one
To make ten ones
And you know why four plus minus one plus ten
Is fourteen minus one?
Because addition in commutative.
Right.
And so you've got thirteen tens and you take away seven
And that leaves five.
Well, six actually, but the idea is the important thing.
Now go back to the hundreds place
You're left with two
And you take away one from two and that leaves...
Everyone get one?
Not bad for the first day.
What a genius.
TEACHING MATH THROUGH THE YEARS
Teaching Math in 1950: A forester sells a truckload of timber for £100. His cost of production is 4/5 of the price. What is his profit?
Teaching Math in 1960: A forester sells a truckload of timber for £100. His cost of production is 4/5 of the price, or £80. What is his profit?
Teaching Math in 1970: A forester exchanges a set "L" of timber for a set "M" of money. The cardinality of set "M" is 100. Each element is worth one pound. 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" for profits?
Teaching Math in 1980: A forester sells a truckload of timber for £100. Her cost of production is £80 and her profit is £20. Your assignment: Underline the number 20.
Teaching Math in 1985: By cutting down beautiful forest trees, the forester 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 forester cut down the trees? There are no wrong answers.
Teaching Math in 1990: By laying off 40% of its foresters, a company improves its stock price from £80 to £100. How much capital gain per share does the MD make by exercising his stock options at £80? Assume capital gains are no longer taxed, because this encourages investment.
Teaching Math in 1995: A company out-sources all of its foresters. The firm saves on benefits, and when demand for its product is down, the logging work force can easily be cut back. The average forester employed by the company earned £30,000, had four weeks holiday, a pension and medical insurance. The contracted forester charges £30 an hour. Was outsourcing a good move?
Teaching Math in 2000: A laid-off forester with four kids at home and a ridiculous settlement from his first failed marriage comes into the forestry-company head office and goes wappy, mowing down 16 executives and a couple of secretaries. He gets lucky when he nails a politician on the premises collecting his kickback. Was outsourcing the foresters a good move for the company?
Teaching Math in 2004: A laid-off forester serving time in Broadmoor for blowing away several people is being trained as a VISUAL C programmer in order to work on Prison IT Security projects. What is the probability that their systems will become infected with a virus that just happens to cause the automatic cell doors to open on their own as of 00:01, 01/01/05?
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