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Re: [Phys-l] Who really failed?



Please excuse the rash of quick comments - I doing this between meetings. Of all the assignments I give: homework, reading quizzes, labs, papers, etc., the only strong correlation that I have found with exam grades is with homework - usually an r^2 of 0.8 or higher. That was also true for the problematic class I experienced this Spring - very weak homework highly correlated with very poor exam grades, good hoemwork with good exams - a correlation of 0.84.

Bob at PC

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of curtis osterhoudt
Sent: Friday, May 21, 2010 9:58 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] Who really failed?

Perhaps our expectation that _each_ class will have a Gaussian distribution of abilities (quantified according to a measure of grades, I suppose), with equivalent means across all classes, and appropriate std. deviation, is a bit silly. You could have just hit a larger than usual deviation.

Do student populations have a "1/f noise" distribution of abilities?

/**************************************
As a species, we are forever sticking our fingers into the electric socket of the Universe to see what'll happen next. It's a trait that'll either save us or kill us, but by god it's what makes us human beings. I'd rather be in the company of people who look at Mars than people who contemplate humanity's navel -- other worlds are better than fluff. ~~Sir Terence David John Pratchett
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________________________________
From: "LaMontagne, Bob" <RLAMONT@providence.edu>
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Sent: Fri, May 21, 2010 7:49:57 AM
Subject: Re: [Phys-l] Who really failed?

[snip]

I have been teaching 28 years. My exam averages have been fairly consistent over the years - falling in the 65-75 range. I always have a core of 3-4 out of 25 students who get in the 90's. However, this past semester, with no change in techniques (except a move to online homework), my second exam had a disastrously low average of 40. It was a bimodal distribution of lots of 25 - 30's and the usual 3 above 90. When I handed back the exams I was stunned at the reaction. Most of the low performers didn't bat an eyelid. They just put the exams aside like nothing had happened. Only two people saw me after to talk about improving their grades. The only other reaction was a parent who called the Dean stating that I couldn't fail a whole class like that.

I had no indictor that such a low average was coming - although the first exam was at the low end of my traditional range. Third exam was back to normal, but a number of low performers had already left the class.

Low averages can happen. When I pressed for feedback I received little insight as to why that average was so low - a few students said they thought there were more conceptual questions vs numerical than my first test.

The Dean took an historical approach to the matter - reviewed my past grading and favorable comments he has received about my teaching over the years. He just chalked it up to the mix of students in this particular class (my other class had the usual distribution of grades.)


[snip the second]




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