Re: [Phys-l] crutches versus shoes

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

I'm not against factor labeling, converting units, etc., but we should ask
ourselves what we are trying to teach our students, most of whom will
never become :scientists. Here are some of my (high school physics) goals:

To think abstractly and logically.
To appreciate and understand the physical world.
To solve real life problems using basic algebra.
To realize that a knowledge of physics is useful in everyday life.

Do we want our students to solve a problem like this?:

A train traveling from New York to Chicago is moving at 110 km/h when the
engineer sees a stalled car near the track ahead. The train brakes to a
halt in 1.2 min with a constant deceleration, stopping just next to the
car. How far was the train from the car when the engineer first applied
the brakes?

Physics is very challenging for most students, especially the concepts.
Students do get bogged down with units sometimes, which can make a
fun/interesting subject like physics even more difficult.

Many students tell me they disliked chemistry as there was way too much
emphasis on "converting units" (the entire year in chemistry). They wanted
to see more "practical" chemistry. I understand what they are saying...


Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
> A deep understanding of factor label, to me, is simply the  
> understanding that you are multiplying a quantity by the number 1,  
> somewhat disguised, and thus ending up with an equivalent quantity.  
> [At least that's one version of what one calls factor labeling;  
> dimensional analysis is another.] It's basic, but easily bypassed. In  
> HS chemistry, my friend and I used to joke about converting units  
> because we decidedly did *not* understand what we were doing. We made  
> up "problems" where you, for example, multiplied by (five kids)/(1  
> toy) and (three boys)/(five kids) and ended up with 3 boy/toys. That's  
> about as much sense as the process made for us. I do not recall the  
> teacher ever explaining the process as multiplying by the number 1.  
> Instead, he just did it on the board, really fast.
>
> Bill
>
>
>
> On Apr 18, 2011, at 5:56 PM, John Clement wrote:
> >  I am not sure what is meant by deep
> > understanding of proportional reasoning.
> >
> > John M. Clement
> > Houston, TX
> >
> > > a) Alas, some folks think the factor label method is a bad thing as
> > >  a matter of principle, because it allows students to solve certain
> > >  problems without necessarily having a deep understanding of
> > >  proportional reasoning and scaling laws.
> >
> > _______________________________________________
> > Forum for Physics Educators
> > Phys-l@carnot.physics.buffalo.edu
> > https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l