Re: [Phys-l] Mass and Energy

[John Denker <jsd@av8n.com>]

Hugh Haskell wrote:

> When I started teaching, I quickly found that, even though we were 
> using SI almost exclusively, units still were a barrier to 
> understanding, and they spent more time worrying about which units to 
> use where than they did trying to figure out what was going on. So I 
> decided to simply remove that impediment from the playing field and 
> always use strictly SI units, at least for the first semester. They 
> spent a lot of time in chemistry classes worrying about unit 
> conversions, so I figured that I would leave that to the chemists, 
> since they seemed to enjoy that sort of thing. 

To say it in my own words:

  a) As a junior, in chemistry class, Johnny learned about unit
  conversions.

  b) As a senior, in physics class, Johnny knows so little about
  unit conversions that it is "a barrier to understanding".

It seems that item (b) is a pretty sad commentary on item (a).

In particular, it would seem that "learned" might not be the right
verb in item (a).  I don't know what did happen, but evidently
Johnny did not _learn_ unit conversions, not in any useful sense
of the word.

=============================

> When I did, I found 
> that understanding seemed to come quicker, and once they understood 
> what was going on, the unit problems pretty much went away. When they 
> were able to concentrate on learning physics, without having to mess 
> with unit conversions, it got easier, and when they later ahd to face 
> problems with unit conversions, they didn't seem nearly so difficult 
> to them, and they were able to incorporate them with only minimal 
> effort.

OK!