Talk:FHSST Physics/Units/Introduction

moles
clarkfreifeld: In the table of base units, I changed "amount of substance" to "countable amount of substance" for the definition of the mole, so as to distinguish from mass, which, to me would be more aptly defined as "amount of substance." I don't know if that's now more confusing and just getting ahead of the game.


 * I actually think it adds too much detail. When discussing moles in the context of using them, I would suggest going into depth, making sure student's know that a mole is just a number (~6.022e23), just like a dozen (12) or a score (20) or a ream (500) is a number. A mole makes sense when counting 10^23 atoms. I think "countable amount" only confuses things for students who don't yet know what a mole is.


 * On the other hand, mass is not an amount of substance. It is defined by two equations: Inertia (F=ma) and Gravity (F=m1*m2/G/r2). (As an aside, the fact that these two definitions of mass are equivalent to the precision people have been able to measure is actually quite astonishing, and the subject of ongoing research.) The fact that mass is often used to measure the amount of a substance is just an application of the nearly constant acceleration due to gravity on Earth's surface.


 * Thus, both grams and moles measure quantities that necessitate detailed discussion to understand completely. This is the first page of the first chapter of a student's first real physics class! I suggest leaving the definitions vague, and let student's inquiry guide them to the answers they are interested in for now. Otherwise, bring up detailed discussion of grams and moles when appropriate in the context of the text.
 * Zolot 17:53, 28 November 2007 (UTC)

"Units" versus "Measurements and Units"
I'd like to suggest a change to the general theme of this chapter. It currently does a good job teaching about units in an abstract sense. However, I feel it is also important to emphasize that all of science, and particularly the use of "units", is based on measurement. I am new to this wiki, so I have not started editing this existing text. My inclination is to go so far as to change the chapter title to "measurement and uhits." This change in emphasis would also facilitate adding more pictures to chapter (as suggested on the PGCE comments page) and encorporating laboratory into the class. In the U.S., where I live, it is easy to emphasize the need for measurement and emphasis of units in a very accessible way -- by focusing on length measurements. Have students measure their own heights in feet/inches and meters. Drive home the point that physics is not just a class full of mathematics -- word problems. It has to do with things you can touch and feel AND MEASURE. The math is only there to make the measurements meaningful and express the real world in the powerful language of numbers and relationships.

Awaiting feedback from the current contributors before I begin making changes to the existing curriculum. Zolot (talk) 05:07, 15 December 2007 (UTC)