[Phys-L] Re: Private Universe and the Seasons

[rmcder at PEOPLEPC.COM (R. McDermott)]

----- Original Message -----
From: "jbellina" <jbellina@SAINTMARYS.EDU>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Monday, August 08, 2005 2:19 PM
Subject: Re: Private Universe and the Seasons


> Two comments
>
> First, I think changing students belief systems takes more than getting
> them interested.  Sometimes it seems the new experience has to really
> get their attention, almost wack them over the head, before they begin
> to rethink.

"Really getting their attention" does not differ significantly from "getting
them interested"; simply a matter of personal definition.  That doing this
is, or can be, difficult to achieve is certainly true ;-)  One of the best
ways to do this is through a discrepant event (as you seem to suggest
above).

> I support this by having students overtly discuss their
> predictions and experiences with each other, working to come to
> consensus before we have a whole class discussion.

A good way to do things if sufficient time is available.  I do as much of
this as I can, but since NY has a defined curriculum that must be completed
and is tested, I feel that I have to be somewhat more directive than I would
prefer under more ideal circumstances.

> Second, I have found ray diagrams less then obvious to students unless
> you spend some time working with them in a simple context.  I use
> McDermott's...no relation??

No relation (unless we were to trace our roots back to Ireland, where I
wouldn't be surprised to find a familial connection - McDermotts seem to be
predominently from two western counties).

> ...material on projecting light through
> holes to do this.  We take ray diagrams as simple and straight (pardon
> the pun) forward.  My experience is that they are not to the
> uninitiated.

I've always felt that I've had pretty good success using them, but I spend a
couple days early on working with them in a simple Law of Reflection
context.  We emphasize that "what YOU see is a result of light coming from
the mirror to your eye" and "the source of those rays coming to your eye
appears to be the image".  That seems to set them up fairly well for the
idea of locating images (and the objects themselves).