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Re: [Phys-l] Old News That Stays News



Now I understand Gate Keeper. Never having succeeded in the rote method* and not subjected to the new maths, she often assists w/ the tricks JD suggests. She's ten years younger.


* An example of why they failed. In seventh grade the rover and flash card method. The teacher flashes an arithmetic question; the rover stands next to the seated; the person who answers first continues as the rover. Stupid, nicht wahr? I distinctly remember at the time thinking that she had it backwards, but was too cowed to suggest the slow one should be the rover.

bc thought by the UCSB Physics Dept. would fail physics because his 1954 Thurstone Q score was only 28.

On 2008, Jul 20, , at 13:46, John Denker wrote:

In the context of

a child today might reason that 5 is half of 10, and 88 times 10 is
880, so 88 times 5 is half of that, 440 -- poof, no pen, no paper.

That's not wrong, but it's not optimal for illustrating the point,
because the more traditional 400+40 can also be done quite easily
without pen or paper.

Here's a simpler and IMHO better example: The task is to add 198 plus
215. The easiest way to solve this problem in your head is to rearrange
it as (215 + (200 − 2)) which is 415 − 2 which is 413. The small point
is that by rearranging it, a lot of carrying can be avoided.

One of the larger points is that it is important to have multiple
methods of solution. This and about ten other points are discussed at:
http://www.av8n.com/physics/thinking.htm#sec-devious

On 07/20/2008 12:11 PM, Wes Davis asked:

How do they teach multiplication of 88 by, say, 7?

I don't know how "they" teach it, but here's how I might do it:
7 = 5+2

88 * 7 = 440 + 160 + 16
= 600 + 16
= 616

No pen, no paper ... in less time than it would take me to find a
calculator ... or find pen and paper for that matter.

Although the more traditional 560 + 56 can also be done quite
easily without pen or paper.

===================================

On 07/20/2008 11:25 AM, chuck britton wrote:

It was in the second grade that I finished up a one and two digit
exercise in addition and decided to go back and repeat the problems
with subtraction instead of addition.
This was just to fend off boredom.

When I came to the somewhat unexpected 'problem' of subtracting seven
from four - I just made up a new notation - the answer is clearly
'three in-the-hole' so I wrote down the three and drew a circle
around it to signify 'in-the-hole'.

I had written down the 'correct' addition answers so the teacher
wasn't bothered too much with the extra scribbling.

I know a lot of people who got in trouble for doing stuff like that ...
including more than a few who got classified as "learning disabled" (or
as they called it back in those days, "retarded").

The funny part comes when Momma Bear finds out about this. Momma Bear
knows what's what, because /she/ had the same problem when she was a
kid, and now has a PhD in mathematics. So she goes to the principal
and says "The kid has been talking since she was 10 months old, has
been riding a bike since she was 3, has been able to cook dinner for
five people since she was 5, has her own library card /not/ restricted
to the children's side of the library, and has her own slide rule.
There is nothing wrong with the kid. You'd better figure out what is
wrong with your school right the hell now." They send the kid out
for a couple days of testing, and decide to cut the kid some slack.

Then 25 years later, the kid has kids of her own, and ..........

The not-so-funny version of this story is kids who (a) don't learn to
sublimate their boredom but (b) don't cause enough trouble to get noticed,
and (c) don't have a Momma Bear who knows what to do. Such kids just
slide along, year after year, getting lousy grades but not getting any
help.

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