Archive for September, 2008

Having it both ways

Tuesday, September 30th, 2008

There’s some argument on the merits of partial credit – giving students some points for getting at least part of a complex answer correct.  Sometimes, partial credit is beneficial – but the existence of partial credit causes another problem:

Some students simply won’t commit to an answer, hoping to somehow pass on a wave of partial credit.  As an example, consider the question below.  It’s part of a lab write-up where the students measured the pH of a solution of sodium hydroxide using pH paper and other indicators.

Question: Was the solution acidic or basic? _________________
Student answerAcidic, with the presence of base

Of course, the correct answer is “basic” – which was very obvious if the student had even glanced at the directions for using the indicators.  But instead of doing that, this student just thought he’d wing it, get done with the lab write-up a whole minute faster, and try to get points for his answer anyway.

I imagine that students keep trying this strategy because it has worked somewhere before.  But not today.

Some debate thoughts

Saturday, September 27th, 2008

Last night, I watched part of the Obama-McCain debate.  Since I only saw about the last half of the debate, I’m not going to try to say who “won”, overall.  But here are a few assorted thoughts.

  • Like many other folks, I found it off-putting that McCain couldn’t bring himself to look at his opponent.  He also took every opportunity to sneer condescendingly at Obama – talking no fewer than five times about how Obama was “naive” or “didn’t understand” some point of foreign policy.  Oddly enough, he did this even on Georgia. where Obama and McCain are rather similar.  For the part of the debate I saw live, McCain was in full-on “bitter old man” mode.  Bitter, obviously, that some young guy is running for the office that he is rightfully entitled to.  Especially bitter that this young guy is currently winning.
  • If you have to call yourself a meverick, are you really a maverick?  That’s like telling everyone how cool you are instead of actually being cool.
  • How many wars will John McCain start by accident?  Unless he’s much more in control of himself across the table from leaders of rival nations than he was at the debate, quite a few.
  • McCain dug himself a nice, deep hole with the flap over “preconditions”.  Perhaps he should go discuss this with his advisors?
  • I’d like to have seen Obama hit McCain a little harder.  For instance, there was no mention of McCain’s rug-buying expedition with Lindsey Graham, where McCain McCain visited a market while under heavy military guard and then claimed he walked around freely.  Still, I understand that Obama needs to not be seen as overy angry.  He must be the cool-headed leader that Americans can depend on in a crisis.

How could I have missed the most crucial issue of all?  NotVeryBright urges us to consider the flag pin issue! Obama had a flag pin, McCain didn’t!

Keeping up with the meltdown

Thursday, September 25th, 2008

I hear that John McCain has “suspended” his campaign so that he could swoop back to Washington to save our financial industry.

Only he hasn’t actually read the details of the plan the administration want the Congress to pass.

Asked by the NBC affiliate in Cleveland about whether he was prepared to support Paulson’s plan, McCain said, “I have not had a chance to see it in writing. I have to examine it.”

I’m not campaigning, but I do have a pretty busy schedule.  But my lab students have just started plotting their data for the freezing of acetic acid.  That gives me a few moments where I don’t have much else to do.  Here’s Paulson’s plan.

Now that I’ve read the plan (and my students are still plotting), I have some qualms with it.

Sec. 6. Maximum Amount of Authorized Purchases.

The Secretary’s authority to purchase mortgage-related assets under this Act shall be limited to $700,000,000,000 outstanding at any one time

Aren’t conservatives generally against “throwing money at a problem”?  That’s always the line wen someone wants to use a little more money to improve education.  7×1011 dollars is a lot of money.  It’s about $2300 from each person living in the USA.

How will this sum of money help address the root causes of the meltdown?  At least with education spending, you can generally point at a few things that can be fixed with the money (class sizes, worn facilities, etc.).  Does buying bad debt off of financial institutions discourage them from taking on more bad debt in the future?

Sec. 8. Review.

Decisions by the Secretary pursuant to the authority of this Act are non-reviewable and committed to agency discretion, and may not be reviewed by any court of law or any administrative agency.

Anyone else have problems with this?  Lack of oversight of the financial markets is part of the reason we’re in this mess.  How will giving someone a bunch of our money and agreeing to not hold him accountable in any way for it fix the problem?

Friends, does your milk powder taste different lately?

Monday, September 22nd, 2008

It looks like there’s trouble in China.  Supplies of milk powder meant for Chinese infants are tainted with melamine – the same chemical found in last year’s dog-food scare.

On Sept. 17, China’s minister of health, Chen Zhu, announced that three babies had died, more than 150 were suffering from acute kidney failure, and an additional 6,000 infants had become sick after drinking milk made from milk powder tainted with melamine.

Now you might be wondering why on earth a company would add melamine to powdered milk.  Could it have been accidental?  Or was there some reason to add this compound?

Consider this:  The amount of protein in foods is often determined based on total nitrogen content.  That’s because proteins contain a fairly regular amount of nitrogen – about 16% by mass.  Take the total nitrogen content, multiply by a conversion factor, and you have a good estimate of protein content of the food.

Take a look at melamine.

Melamine, C<sub>3</sub>H<sub>6</sub>N<sub>6</sub>.  Nitrogen atoms are indicated in blue.

Melamine, C3H6N6. Nitrogen atoms are indicated in blue.

Simple assay methods for total nitrogen content can’t distinguish the nitrogen in melamine – which is about 67% nitrogen by mass – from the nitrogen in proteins.

The tested substance appears to have a higher protein content than it actually does – since analysts assume that almost all the measured nitrogen comes from actual protein.  This is a reasonable assumption for uncontaminated materials, but is open to abuse by the amoral.

It amazes me that the Chinese were caught by this same ruse again.  You’d think that after finding melamine added to pet food, the Chinese government would have gone ahead and made sure nobody was adding it to food for humans.

Brunswick Stew-pid

Thursday, September 18th, 2008

Looks like our northern neighbor is affected by the same disease that Upstate SC has:

the Brunswick County school board began discussions on teaching creationism alongside evolution – something all four board members present showed a strong interest in. The talk began after Joel Fanti, a parent and graduate of the school system, told the board that he considered it a problem to teach evolution as a fact and that science teachers should include creationism in the curriculum, as well.The audience applauded.

… a case of The Stupid.  At this point, it seems that the state will squash this little Stupid outbreak.  The higher-ups in the NC school system recall the Dover trial.  This, after all, would be a more blatant attempt than the one in Dover to replace science with religion in the science classroom.  A lawsuit would almost certainly follow.

One more disturbing point:

Teachers have alternative assignments for students whose parents have objections about evolution, but students are still assessed on the topic in state tests

Lovely.  Parents can opt their kids out of biology, but teachers are still held responsible for students whose parents won’t allow them to learn?

Palin’ in comparison

Wednesday, September 17th, 2008

I haven’t had a whole lot of time to blog lately, but I can’t resist laughing at the culture wars.  Yglesias links to this post from an “oasis of rational conservatives”, titled “THIS IS ALL YOU NEED TO KNOW”:

THIS IS ALL YOU NEED TO KNOW

THIS IS ALL YOU NEED TO KNOW

So … the Democratic nominee for President can ride a bike, while the Republican nominee for Vice President can stand in front of a motorcycle?

But this post really compares apples to oranges.  They should have McCain on a motorcycle (making sure to hide the scaffolding holding him up).  That, or find a picture of Joe Biden on a bike.

Be Prepared

Monday, September 8th, 2008

This blog has been very quiet lately.  Sorry about that, but when you’re preparing for five labs a week in addition to lecture courses, things get a little … hectic.

That said, we’re four weeks into the semester down here, and we’ve started our labs.  I normally push the start of labs back a week, so as to avoid having people add my class after we’ve already done a lab and discussed lab safety.

A bit of the lab schedule

A bit of the lab schedule

The Labor Day holiday pushed the start of the “real” experiments back even farther – ample time for everyone to pick up one of these.

The laboratory notebook, also known as a 50-cent compostion book.

The laboratory notebook, also known as a 50-cent composition book.

… so why is it that half of the class comes to lab without even having attempted to buy a laboratory notebook?  It’s not like I’ve forced students to buy something exotic like the $25 lab books I had to buy when I was an engineering undergrad.  Just about every store in the area that sells school supplies stocks these composition books!

Or were these folks simply not paying attention?

You know, if we could figure out how to solve America’s attention-deficit-disorder problem, that would go a long way to solving our other problems.  Just sayin’. 🙂