Re: [Phys-L] effective teaching of scaling/ratio use

["John Clement" <clement@hal-pc.org>]

So my question as usual is how much gain do you see on a standard test of
thinking skills like the Lawson test??
John M. Clement 

> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf 
> Of Richard Heckathorn
> Sent: Saturday, December 20, 2014 12:38 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] effective teaching of scaling/ratio use
>
> Greetings, if you go to my website listed below, select the 
> more column, select function and scaling, you'll find a 
> number of activities that I use with my students.
>
> You can also select the Honors column, 01 measurement and 
> analysis where you will find my scaling materials.
>
> To begin, I used three wood blocks,
> 1x1x2 inches
> 2x2x4 inches
> 4x4x8 inches
> One can easily let the students examine the scaling factors 
> and the area and volume relationships.
>
> Dick
>
> Have a Great Day
>
> Website rheckathorn.weebly.com
>
>
>
> > On Dec 20, 2014, at 1:22 PM, Richard Heckathorn 
> <geepaw@wowway.com> wrote:
> > Sorry, I hit the send button before I was finished. I 
> should have said that strength increases by a factor of four 
> and weight  increases by a factor of eight.
> > Thus as an adult, one is four times stronger and eight 
> times heavier. No wonder a two-year-old has so much energy as 
> their strengths to weight ratio must be larger to accommodate 
> the reduced strength to weight ratio as an adult.
> > Dick
> >
> >
> >
> > Have a Great Day
> >
> > Website rheckathorn.weebly.com
> >
> >
> >
> > > On Dec 20, 2014, at 1:15 PM, Richard Heckathorn 
> <geepaw@wowway.com> wrote:
> > > Greetings, I have been told that a two-year-old, when an 
> adult, has increased by an approximate scale value of two.  
> If one takes this as a starting point, then all areas 
> increase by two squared or four times, and all volumes and 
> weight increases by two cubed or eight times.
> > > Have a Great Day
> > >
> > > Website rheckathorn.weebly.com
> > >
> > >
> > >
> > > > On Dec 20, 2014, at 1:25 AM, John Clement 
> <clement@hal-pc.org> wrote:
> > > > Explicit teaching of ratio techniques does not really 
> change their 
> > > > attitudes about proportional reasoning.  What they really 
> need is a 
> > > > dose of "Thinking Science" by Shayer, Adey, Yates. If you look at 
> > > > what they do, you might be able to do some of it in class.  The 
> > > > method uses exploration first where the inapplicability of their 
> > > > existing math paradigm is insufficient to make sense of the 
> > > > situation.  Then they have the students do bridging to other very 
> > > > different situations.  This is the application phase.  At no time 
> > > > are they told the explicit technique to use for the 
> application phase.  However, there is supposed to be a class 
> discussion about the exploration.
> > > > The idea of teaching scaling is nonsense if the student has no 
> > > > "understanding" of proportional reasoning.  It will just 
> be another 
> > > > memorized thing to be used in the specific problems in 
> which it is 
> > > > presented.  Actually half is about the right number.  25% of 
> > > > advanced students and 75% of regular students do not use 
> > > > proportional reasoning.  You can find out the ratio by 
> giving the Lawson test.
> > > > I always recommend reading "Really Raising Standards" by 
> Shayer & Adey.
> > > > John M. Clement
> > > > Houston, TX
> > > >
> > > > > As John Denker routinely points out, using scaling laws 
> (or ratio 
> > > > > and proportion) is extremely valuable and powerful.
> > > > > This tool has great value beyond physics, reaching into 
> carpentry, 
> > > > > economics, and even flying airplanes :).
> > > > >
> > > > > My quandry is how to get students to actually use it.  I 
> > > > > demonstrate it in class, I give exercises and show 
> solutions, but 
> > > > > when it comes time for a test or quiz, about half my 
> students act 
> > > > > like they have never seen the technique, even when I 
> tell them "use 
> > > > > ratio and proportion like you did on the homework and classwork."
> > > > >
> > > > > The other half can't seem to grasp how to use the 
> general concept 
> > > > > on a new law. For example, after using the technique on the 
> > > > > electric field of a point charge I then tell them (and 
> show them) 
> > > > > the far-field distance behavior of the dipole E-field.  
> This isn't 
> > > > > the only situation. It seems they don't really understand the 
> > > > > concept of scaling.
> > > > >
> > > > > What methods have any of you found which are effective in having 
> > > > > students grasp the concept of scaling and apply it to a "new" 
> > > > > relationship they haven't been drilled on before?
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