Re: [Phys-l] What are your answers for this teacher?

[Boyd Weiger <weiger.science@gmail.com>]

Let me throw this into the mix...

Here's the MN Academic Science Standard 
<http://education.state.mn.us/MDE/Academic_Excellence/Academic_Standards/Science/index.html> 
for Newton's 2nd Law for the physical science course:
9.2.2.2.2 - Explain and calculate the acceleration of an object 
subjected to a set of forces in one dimension (F=ma).

So if I use standards-based grading, and a student is unable to meet the 
standard due to lack of algebra skills, am I assessing the standard or 
am I assessing the algebra skills?

I truly am interested hearing what you all have to think about this 
since I am not currently using SBG, but I am planning on implementing it 
next fall...

I teach 9th grade physical science, and my students' math skills are all 
over the board.

Thanks!

Boyd Weiger

On 4/9/2011 10:19 AM, Bernard Cleyet wrote:
> Today's first PTSOS post:
>
> My 9th grade physics students were taught a method for solving speed problems in middle school that does not require algebra. The variables are separated in a diagram of a triangle (or a circle). When you cover up the variable you are solving for, the diagram shows you the recipe on how to solve the problem. If you're not familiar with what I'm talking about, here's a link to an example using Ohm's Law: http://www.electronics-tutorials.ws/dccircuits/dcp_2.html
>
> I have avoided use of this device for a variety of reasons. First of all, it has zero meaning. I feel that it is important to reinforce my students' algebra skills, which this method completely skips. I also prefer Hewitt's method on using equations as "guides to thinking" which these triangles/circles avoid. Finally, I have found in the past that various memory devices in math (e.g. FOIL, cross multiplication, etc.) have limited function and students tend to use them incorrectly much of the time.
>
> However, I am wondering if I should reconsider my stubborn position. I have had many students approach me this year showing me the triangle and claiming "here's an easier way to solve the problems!" In addition, at the NSTA conference I was introduced to a text entitled "Active Physics" by Arthur Eisenkraft which uses the circle for every equation given in the book.
>
> Again, these are 9th graders I am teaching, so maybe I should not be such a stickler on going through all the algebra. This device is primarily used for "plug and chug" problems anyway, which have little meaning themselves.
>
> Do any of you use this method with your students? Have you found it useful? Do you have any tips to make it more meaningful and universal? Do you see it as a hindrance?
>
> Thanks in advance for your collective knowledge and wisdom!
>
> bc thinks the picture is not a model.
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