Re: [Phys-l] glassware needed

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

Well of course immersion heaters can scorch juvenile skin even more, and
when dropped when plugged in they can splatter hot metal.

The problem with the abstract mathematical relationships is that students do
not understand them precisely because math jumped from purely concrete, to
extremely abstract without tying them together.  One needs to have the
student do "concrete" experiments that model relationships, and at the same
time have them develop the equation as a model for the relationship.  They
need to do graphs, descriptions, pictures, and equations at the same time.
Then they need to do applications, preferably ones that bridge to different
situations.  None of this requires absolutely accurate calibration of the
apparatus.  It is not a matter of just making the abstract concrete.  It is
tying them together, and using bridging, and a well structured model.

Again, LOOK at the real time physics and interactive lecture demos for some
of the ideas that work.  They are structured very well to produce better
understanding of heating.  After looking at them carefully in detail, you
may be able to see the way that the learning must proceed.

So again, the absolute calibration of an apparatus may be a good activity
for us, or for students who have already internalized good models of heating
and have proportional reasoning.  But worrying about such things for intro
students is like arguing about how many angels dance on the head of a pin.
The already mentioned labs use ordinary Styrofoam cups, pennies, immersion
heaters, and precise pulsers along with a temperature sensor and a computer.
They used to come with some research papers showing how student
understanding increases, and also a conceptual evaluation of learning.

These labs are not perfect, but they are MUCH better than the usual labs,
and at least have research results validating their results.  They also come
with very complete instructions.

John M. Clement
Houston, TX


> At 12:39 AM 1/2/2009, you wrote:
> > Well if you look at the misconceptions of students which are addressed by
> > the RTP and ILDs, the important factor for students to understand is how
> > relative factors change the temperature-heating relationships.  Simple
> > experiments which just measure how much the temperature rises for a given
> > input of energy do not address the misconceptions....
> > > > John M. Clement
>
>
> Folks who want to make concrete some relations which may help student
> understanding might consider the virtues of hot pennies.
> Adding a hot penny at a time to a sample of cold water might well
> show off a staircase of temperature versus number.
>
> This is essentially your recommendation, John, but rendered concrete,
> with all its possibility of scorching juvenile skin, it's true!
> [What's so intuitive about an invisible pulse of electrical heating,
> anyway?]