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Topic: [math-learn] significant digits
Replies: 16   Last Post: Feb 28, 2002 7:49 PM

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Suzanne Alejandre

Posts: 113
Registered: 12/3/04
[math-learn] significant digits
Posted: Feb 27, 2002 9:56 AM
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As a result of mentoring this week's Math Forum MidPoW, Altius,
Citius, Fortius, I have been thinking a lot about significant digits.
Let's see if I can give you a quick summary of the problem so you'll
be able to see what I'm talking about.

Various Olympic and World record times for both speed skaters and
runners are given for the 1500 meter races. The first question asks
students to determine whether any of these athletes would be arrested
if they were skating or running at their record speed in a 25 mile
per hour residential zone. The idea of significant digits is
appropriate to discuss as far as how students express their answers
but it really became an issue when I started reviewing the bonus
question responses!

The bonus question is:
"Let's imagine the speed skater and runner from each year starting a
race side by side. How far behind is each runner when the skater
crosses the finish line?"

All of the students who did the bonus, were getting answers just a
tad different than the ones I had and yet there was no real
consistent difference. Annie Fetter came to the rescue and worked out
the solution using both my method and the students' method and
realized that the reason that my numbers did not agree was because I
had rounded off too much and too early. It made me realize what an
important, yet perhaps often ignored, subject significant digits are.

So, given this background information, here is what I'm now very
interested in hearing about from you:

1. At what age do you teach your students about significant digits?
What age do you think this is normally taught?

2. Do you have a favorite activity that you use to teach your
students about significant digits?

By the way, you're welcome to view the problem itself by going to - if you'd like to see the clues and
all, just submit but tell me that you are a "math-learn" member just
viewing. Once you've gotten in to the problem area, all of the
features will be available for viewing.


Suzanne Alejandre
Educational Resource and Service Developer
The Math Forum @ Drexel []

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