Tired

Tired of explaining how to work out the simplest formula for aniline to the same bunch of students seventeen times over. Including a couple students who’ve come by for multiple explanations.

Tired of students worried about every last little point of their grades, when they should be spending more time thinking about the subject. Tired of students who want more time on the test – when they’re likely to do poorly anyway because they haven’t bothered to even LOOK at the homework assignments.

Tired of students turning out to misunderstand some of the most elementary concepts… or ignoring my general advice (“watch the units! let the units guide you!”) until I’ve walked them through six problems in an hour and finally something clicks and they go “ohhhh! so that’s what you meant!”

It’s not that I don’t care. It’s not that I don’t want them to do well; it’s not that I don’t want to find better explanations for the idea of a mole. It’s not that I want to write off half the class as clods incapable of grasping the obvious fact that molecules react as individuals but get weighed out by the trillion as grams, and that sometimes we need to figure out how many molecules there are in a certain number of grams and it’s not really THAT hard.

It’s that there’s 121 of them and 1 of me. It’s that there’s only 168 hours in a week, and that some are more worried about possibly missing out on 0.015% of their final average because they just couldnt’ get to class because they were snowed in, perfesser, really! I can show you pics if you want!!!!1 than they are that they missed 3 dirt-simple questions on the last in-class quiz. (For instance: These three molecules have different weights. One’s very heavy; the other is very light; the third is in between. Which will you need the most of to make a gram? 30% picked the heaviest one.)

And… it’s the fact that there’s 121 of them this semester, just as there were 121 of them last semester, and there’ll be another 121 next semester. I’m still hoping to be here next semester to deal with them, but eh.

Clearly I need a better approach. There is either a better way to explain some of these concepts to these students, OR I’m wrong in my hypothesis that every single one of them is capable of understanding it.

Or both.

Last semester’s students weren’t this bad… were they? The memory plays tricks. Last semester everything was new and exciting; this semester it feels like leftovers. Leftover students who didn’t start taking chemistry when the other kids did; leftover lectures because I’m too busy swimming around in worksheets that need grading to do more than warm up the same slides as before.

The lectures worked fine last time!

Didn’t they?

I need more to do. Ironic to say that. I need stuff to do that doesn’t involve teaching people – as much as I enjoy it, usually, I don’t like it being ALL that I do… for the same reasons I’ve never had an urge to go teach preschool.

I posted earlier about why I like teaching freshmen. I meant every word then and I stand by it now. But… I need to not just be teaching freshmen.

Unit Analysis Game!

One of the concepts that the freshmen need to pick up very early on is referred to sometimes as “unit analysis” (AKA “factor analysis” or “dimensional analysis”). It’s basically the idea that (1) a lot of chemistry “word problems” are really conversions from one unit to another, or involve conversions; and (2) the units themselves tell you how to work the problem.

For instance, they had trouble with this problem: Neon atoms are arranged in a line 2.54 miles long. There are 5.76 x 10^13 atoms in the line. What is the diameter of the neon atom, in Angstrom units (10^-10 m)?

(Yes, that wording is completely unrealistic, but that’s not the point. This avoids the density, solid structure, and mole concepts that would show up in a problem like “a cube of iron weighs 1.24 g, calculate the diameter of an iron atom”.)

It’s an easy problem, but about half of them had some trouble with it, and about 10% of the class is still pretty shaky on it. Basically, convert miles -> meters -> angstrom, and then divide by the number of atoms in the line. See? Unit conversions; there’s no “chemistry” needed to solve the problem. (Some of them picked it up when I pointed out that it’s exactly the same as “how big is a golf ball if 10 golf balls form a line one foot long?”)

The “unit analysis” part of it is based on multiplying the original ratio (2.54 miles / 5.76 x 10^13 atoms) by different constant ratios of units: 1.6 km = 1 mile, so multiply the original ratio by (1.6 km / 1 mile) gives you the same ratio expressed in km / atom. Then change that to meters / atom (using 1000 m / 1 km), finally to angstrom / atom. Without including the units, students can get confused: do I multiply or divide by 1.6? With the units, they can’t do this: If you multiply the wrong way: 2.54 miles * 1 mile / 1.6 km = mile^2 / km, which isn’t a useful unit.

It’s pretty trivial at this stage, and there’s other ways to get it right – as some of them point out. But later on, they can use the same approach with stoichiometric ratios to work out all kinds of problems that do involve chemistry.

Here’s the game part: Showing it on paper or on the blackboard doesn’t enforce the idea of fixed ratios that we can string together at will to reach the right answer. I want a set of plastic tiles that have the different unit ratios on them (e.g., a tile showing “1.609 km / 1 mile”, on the reverse it shows “0.6213 mile / 1 km”), that they can actually move around. (Tiles that just say “mile” and “km” separately wouldn’t work.) Also “prefix conversions”, like “1 / 1000 milli-”.

Oh, and I need them cheaply enough to be able to get about a hundred copies.

Found a procedure for “DIY shrinky dinks” – polystyrene sheet can be heated to shrink down to about a 1/3 of its original width/length, and 5-6 times its original thickness. Smallparts.com sells high impact PS sheet that should shrink up to about the right size… Too bad the hobby shop in town is closed on Sundays!

Teaching Freshmen

It’s a huge responsibility to teach a freshman class.

A lot of faculty look at it as an unpleasant obligation. Big classes, lots of “busy work” grading, only covering the basics without really getting into the interesting parts of the subject. Lots of “hand holding” and reminding them of every little thing. And all of that’s true.

It’s also an opportunity, and a responsibility.

Before, I’d taught seniors and grad students. They already knew they wanted to be chemists, or chemical engineers, or a doctor in one case. My “influence” over them and their future was limited – perhaps I encouraged them towards my particular interest, or left them with a new appreciation for something that they’d thought sounded dull. They mostly made A’s and B’s, so not a lot of effect on their transcripts. I don’t know that being in my class last year really changed anyone’s life. (Which may be a good thing.)

Freshmen are a lot more volatile. I’ve had four students drop so far, out of 131. Some have changed their major, partly due to this class. One isn’t going to be a doctor any more. Those are just the “major” impacts that I know about.

I’ve been trying to remember my own general chemistry class; I remember a lot more about the professor than about the details of the class. I doubt very much that he had any particular intention of nudging me towards following in his footsteps. And yet he did – not from any specific thing that he said, but from the enjoyment he brought to teaching, and from the respect and patience he had even for the students slow to understand.

The responsibility, when teaching freshmen, is that casual remarks and attitudes can make a far bigger impact than the subject itself. The opportunity is to make those impacts positive ones.

Really working on that. And I pray that I never stop working on that.

Chemistry formatting

Writing chemical formulas and equations in MS Office is a pain in any body part you care to name.

Yes, you can put in the subscripts and superscripts by hand. It takes a while, it’s slow, and there’s no checking to make sure that the braces go in the right spots. Excel, of course, doesn’t like subscripts and superscripts at all. Charts and graphs wind up with incorrect formulas which we have little choice but to tolerate.

Until now.

Well, actually, I just found out about the solution now. Looks like it’s been available for quite a while, but it hasn’t received NEARLY enough attention.

Dr. Christopher King, a professor at Troy University in Alabama, has created a wonderful set of macros, for Word, Powerpoint and Excel. With these macros, click the button and suddenly “CuSO4*5H20″ gets formatted properly.

It’s not quite perfect; the macro for the Office 2007 products doesn’t do the expected thing for complex ions (for instance, [Fe(CN)6]4- ought to be written as [Fe(CN)₆]^4- and the macro leaves it as [Fe(CN)_6]4^-. It works just fine without the square brackets, though: Fe(CN)64- turns into Fe(CN)₆^4-. This seems odd since he’s an inorganic chemist…

Still, it’s a wonderful wonderful tool. I hereby volunteer 2 hours of my time each year to his service, out of the countless frustrating hours preparing lecture slides that this will accelerate.

(Using LaTeX makes it more fun anyway. The package to use there is “mhchem”, which does the same kind of automatic formatting.)

Best school answering machine message

From William Dembski:

I’m told that the Maroochydore High School, Queensland, Australia, staff voted unanimously to record the following message on their school telephone answering machine, prompted by a school policy requiring students and parents to be responsible for their children’s absences and missing homework. Apparently, the school and teachers are being sued by parents who want their children’s failing grades changed to passing grades — even though those children had double-digit absences during the semester and didn’t do enough work to finish their classes.

The message: Listen

Texas points the way

The Texas State Board of Education recently revised its science standards. Of particular concern was the language about how “evolution” is to be taught. The previous version of the standards specified that students are to be taught the “strengths and weaknesses” of evolution, which caused many Darwinists much indigestion. (“Teach them that it’s got weaknesses? But… but… but it doesn’t have any! Or at least not ones which lowly high school students can understand. How are we so sure? Because everyone that we’ve let into this room with us agrees that it’s so!”)