Re: [Phys-L] Evaluation tests

[Robert Cohen <Robert.Cohen@po-box.esu.edu>]

For a simpler question, how about 5/7 vs. 7/9?

It really doesn't matter as long as you talk to the student and ask how he/she approached the problem.  Some students will convert each ratio into a decimal and then compare the decimals  Others will cross multiply.  Some will subtract the numerator from the denominator.  However they do it, it is important to ask them WHY they think that will work and if they can think of ANOTHER way to get the answer.  A large portion of students simply do not have any idea what a ratio represents and they are just memorizing techniques they have been told they are supposed to do. 

The key point is that students are good at making it look like they know how to do the math when really they have very little understanding of the math.  These same students will try to solve every physics problem by matching with a previous problem and then plug and chug.   These students will do poorly in your class if you require an understanding of the physics.  That is why this kind of diagnostic test is so good.


________________________________________
From: Phys-l [phys-l-bounces@phys-l.org] on behalf of Rauber, Joel [Joel.Rauber@SDSTATE.EDU]
Sent: Tuesday, December 17, 2013 9:40 AM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] Evaluation tests

I didn't consider it hard, but I did have to think, the same amount that you outlined below; I just didn't think that that amount of thinking was hard.  Which brings up the topic of many students I have who don't want to think, if it doesn't come automatically they give up.

-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Bernard Cleyet
Sent: Monday, December 16, 2013 7:32 PM
To: Phys-L@Phys-L.org
Cc: Nancy Seese
Subject: Re: [Phys-L] Evaluation tests


On 2013, Dec 16, , at 15:23, Robert Cohen <Robert.Cohen@po-box.esu.edu> wrote:

> We have found a very strong correlation between students passing this course with a C or better and our own survey, which is based partly on Jerome Epstein's "Basic Skills Diagnostic Test" (BSDT) and focuses a great deal on proportions and the meaning of algebraic letters (variable and unit abbreviations) vs. numbers.  The key is to ask as simple a question as possible that still reveals the weakness.  For example, without the help of a calculator, which is bigger: 25/27 or 15/17?


That's hard for me.  I had to think:  2/17 is larger than 2/27.  Therefore, 15/17 is further from one than 25/27.

Does everyone else just know it automatically?  Or is there another method?

bc fails in a timed test.
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