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Discussion: Understanding Distance, Speed, and Time Relationships Using Simulation Software tool
Topic: Does step size really equal speed?
Related Item: http://mathforum.org/mathtools/tool/13171/


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Subject:   RE: Does step size really equal speed?
Author: reese
Date: Apr 18 2007
Dear KT8,

I looked at the applet, and it was a bit confusing at first,
there is a lot going on there.
However, I think it is consistent in that a step takes an equal
interval of time. That's unrealistic in a way. You wouldn't
expect that a step of, say, 4 feet would happen in the
same time as a step of 2 feet. But it is consistent, and it
fits with what I see as the major point of the applet, which is to
experiment and make predictions. I think it's a very
good exercise in that context.

On the other hand, I would use it in combination with some other tools.
For example, a simliar, but more familiar distance vs. time scenario is in Lisa
Murphy's
"Moving Man" applet.
http://www.mste.uiuc.edu/users/Murphy/MovingMan/MovingMan.html

I would also use graphing calculators and distance sensors to
get at the topic. In combination, these provide powerful opportunities
to develop understanding.

I'm very interested in the presentation at NCTM of the misconceptions that some
electronic tools could reinforce. Could you send me more information on that?

http://www.mste.uiuc.edu/contact?to=George%20Reese

Thanks,
George Reese



On Apr 10 2007, KT8 wrote:
> There is an assumption being made in this simulation that I don't
> agree with. (If this has been addressed in other discussions, I
> apologize). I can take loooong steps very slowly or short steps very
> quickly, so I don't like the assumption that increasing step size
> will cause the "runner" to get there faster. If the x-axis scale
> were in "number of steps" instead of "time," this would make sense.
> One of the sessions I attended at NCTM in ATL was about the
> shortcomings of some electronic manipulatives and how these could
> lead to misunderstandings about the mathematical concepts. Distance
> = RATE * time, not LENGTH OF STEP * time.

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