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Re: Astronomical Unit (AU)



Both of these numbers wedged themselves into my brain before the age
of ten. Captain Kangaroo had a commercial for carrots that included
both the 93 million miles and the eight 1/2 minutes.
Both eight and eight 1/2 eventually fought for top position. Now I
know why. 499 seconds wouldn't have meant much to me as a preschooler.



At 11:14 AM -0800 1/31/01, Leigh Palmer, you wrote about Re:
Astronomical Unit (AU):


>Doesn't this all depend upon the precision required?
>I think 8 minutes is good enough for younger children.
>As they get older then we can get more precise.


Why not say to younger children "Light from the Sun takes
more than eight minutes to reach us"?

(The common scientific literacy test answer would be
eight minutes for adults, and some of those would think
it means *exactly* eight minutes.

A MAJOR part of Scientific Literacy is having a pretty good
grasp of which numbers ARE precise and which are approximate. In the
seventh grade I was told that only counting can be exact. ALL
measured numbers have error.

The number is "out
there". Many also know that the AU is 93 million miles.
That number is good to better than 0.05%, more accurate
than the number Canadian school children learn: 150
million kilometers.)

Leigh

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