Sunday, June 29, 2008

Lab Writing

This is effectively the second part of an article on the objectives of lab classes, where I had limited the discussion to everything except lab reports. I also discussed some of this in the past, stimulated by two articles decrying empty thesis statements and overly effusive language (using verbiage to replace thought) in papers for a upper division or grad-level classes in ed (history of education) and english (Victorian literature). Their complaints are familiar to us in the sciences; I regularly learn new things from folks on that other side of the blog campus and sometimes on my own. [One interesting side result of what I have picked up in academic blogs is the realization that I should talk to people who teach composition or in the social sciences or humanities about these sorts of teaching issues.]

As I see it, the written parts of lab reports address two learning objectives: technical writing, where they have to learn to use numerical results (with uncertainties and units) in complete sentences and clearly define quantities in english rather than with symbols, and critical thinking, where they have to learn to draw conclusions based on quantitative results that a vague fuzziness due to experimental uncertainties as well as separate important from unimportant.

Let's look at these two issues, being careful to include ease of effective grading (assessment is the new magic word) in the design of the task we set our students ... and our TAs(who likely don't have English as a first language).

But first, one word on philosophy: The majority of my students are going on to become engineers, so I am looking more toward that kind of corporate environment (with its memos and reports) than academic research. I hope I can get The Thomas to provide his critique of these thoughts from where he sits in Corporate America, either in a long comment here or in his own blog.

Technical Writing.

I think of this as the requirement that they produce work that looks professional (using correct symbols and notation, such as SI prefixes or superscripts for powers of ten, and grouping the value and its uncertainty inside parentheses) and that communicates their answer without ambiguity. This means using technical terms instead of a catch phrase, and not using a symbol (is it V or v, is it velocity or voltage or volume?) that has not been defined by the writer or in the question.

This requirement is unambiguous and applies everywhere, but I don't mark it off every time I see it made. [I do know profs who take off 0.1 point for every instance of even a minor error, but I don't have that much time to devote to grading.] Instead, I focus attention on specific sections of the report for specific things, such as making sure values are reported correctly (with units) in the calculation section and in the conclusions sections. Those instances are highlighted on my version of the report. [Because of the particular, rather efficient, system I use for grading, this might be one of only two things I am looking for on a particular page of the report.] Nonetheless, I always keep my eye open for an oversight somewhere else in an otherwise good paper. I want everyone to be paranoid about errors of omission such as units or sig figs.

There is also an expectation that answers to questions and some lab exam problems be stated as complete sentences.

Critical Thinking.

This is the real challenge. It takes time and energy to do this right, so I often look at this part of the lab report first or devote a separate day to it, so I can do it while I am fresh. It also requires that the task for the student be well defined, so I try to focus it into just a few areas of the report.

One of these areas is actually easy to grade: the post-lab questions. These are actually a good place to address "conclusion" questions about the implications of the lab results, particularly the ones that require the use of uncertainties to address the significance of an "error" between what is expected and what is found. The key requirement is that they get the right answer and given an appropriate explanation (such as using the size of the standard deviation to judge the precision of their result). A specific question ensures that the student has to address the topic and also means I don't have to go hunting for it somewhere in two pages of conclusions.

I also require that they address specific issues in specific places in the conclusions part of the report. One section has to identify and summarize the most important results of the experiment. It has to be a single paragraph of modest length, like the abstract for a research paper or a memo in the real world. They are marked off for not putting the right things in there or for technical writing errors noted above. I sometimes require that this be a cover memo, while other times I have them call it an abstract. (That helps catch plagiarists.)

The other section must address a particular aspect of a typical "conclusion", such as what followup experiment could be done (and describing it in detail), identifying a real-world situation where this effect is important, explaining what might have caused inaccuracies in their results and how to avoid them in the future, or identifying specific procedures they used that might have contributed to the precision of their results. I vary this question from semester to semester to make it harder on lazy kids who try to use a file from a student in last year's lab.

The real trick is keeping track of students who say the same thing (e.g. didn't read the manual before class to be sure they knew what they were doing) rather than learning from their mistakes and improving their skills in the lab! If they are thinking, these answers should be more than a throwaway line.

Grading Rubrics.

These are essential, and it is essential that they be designed so students who do the experiment and complete all of the calculations with reasonable accuracy and attempt to answer all of the post-lab questions will get a minimum grade of C. Not only is that passing for our college, but it is all that the nearby engineering colleges need to see. That limits somewhat the deductions for egregious errors, but still leaves lots of room to encourage improvement.

It also has to work for me and the adjuncts who work under my supervision. Thirty or so lab reports a week can be a big load for me, particularly when they come due on a week when I also have to grade 250 pages (or more) of exam solutions. It might be an even bigger load for my adjuncts, who have other jobs as well. This requires focus on specific spot checks and clearly defined tasks, as noted above.

I long ago quit cutting them much slack on the initial reports. A warning without a deduction of points has no effect on future behavior. However, I do cut the penalty points for "critical thinking" types of errors to about half of the norm. We go over tech writing skills from day 1, so they are expected to do that part correctly. We also drop the lowest report, so that encourages improvement (but won't help if they skip one of the labs).

Appropos a point Matt made in his blog recently (see below for the link), the max deduction for omission of the separate "conclusion" writing assignments is 20%, although the deductions for flawed contributions are usually around 10% of the total grade. However, other items that require critical thinking make up at least another 20%, if not 30%, of the total. I also include questions of this type (interpret a certain result or write a summary of certain results) on the lab exams.

Other voices.

Matt's recent article about improving lab report conclusions, from the perspective of a graduate student at an R1 university, offers an interesting suggestion: collect some good conclusion sections from physics research papers. (I suppose I could use some of my own!) I'd also like to have a similar collection from industry, since those examples are generally unknown within the physics research or teaching community. As noted below, I would put more emphasis on showing them a good abstract rather than some good conclusions.

Chad Orzel provided his thoughts on the writing style used in lab reports last year, from the perspective of selective liberal arts college with a large physics program. I agree 100% on the evils of the passive voice, but I know where it comes from: our chemistry department. [Comment #15 makes that same observation.] They insist on it. In contrast, I insist on simple declarative sentences that state (in the correct past tense) that a specific quantity was measured, giving a specific result. [Comment #10 gives a nice example of good an bad ways of saying the same thing.] Of equal interest is how a number of comments came from composition teachers who regularly fight the same strange view of what makes good academic writing in their classes. Maybe the problems start in high school!

I also like Chad's emphasis on framing. In effect, that is what I do by trying making them start out by stating the most important result, whether it is a measured value or the verification that energy was conserved to within 10%. A good abstract tells you the important result(s) in a "Just the facts, ma'am" style, much like the headline / sub-headline sequence in the NYTimes.

Read Entire Article......

Friday, June 27, 2008

Mars has Dirt!

Not to be trite, but some of the headlines and quotes have been amusing. "You might be able to grow asparagus in it." What makes this important is that there was no guarantee that the geology on Mars would produce anything like the mix of ingredients we find on earth. Just look at our Moon, which allegedly comes from the same crustal material we farm here on Earth. As emphasized in the BBC story and one from CNN linked below, the soil is mildly alkaline. Bad for azaleas and citrus, but great for lots of other plants and containing the trace elements useful for simple cellular life forms on earth.

(By the way, if you want a clickable image for a high resolution look at the "clumps of rosy red soil", you should use the ones on the main Phoenix news site. You can also follow Phoenix's exploits on its Twitter page.)

Buried in some stories of this important discovery (but prominent in the MSNBC story, which links to a nice little article on is the HOW it was done. Wet chemistry on another planet!

Hey, it is hard enough to do wet chemistry in an intro chemistry lab!

I am really impressed with the work of what I assume is a team of analytical chemists (the folks who focus on developing instrumentation) from my limited knowledge through a grad school friend who is an analytical chem PhD working in the medical field.

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Thursday, June 26, 2008

Ishkabibble CC's budget

This is my own contribution to the college finance 'meme' proposed yesterday.

Ishkabibble Community College, where I teach physics, is a pretty big CC. We are pushing 10,000 FTE students but manage to have enough f-t faculty so only a bit more than 50% of the sections are taught by adjuncts. Unlike colleges described in some discussions I read, quite a few of our f-t faculty teach mostly at night. Budget numbers are below the fold.

Since this is a CC, the total budget has been normalized to 10 M$ even though it is probably bigger than the budget at a lot of 4-year colleges. Capital expenditures are not included because they are budgeted separately.



Our students pay a large fraction of the cost of instruction, but nothing like they do at large universities. However, this makes our budget very vulnerable to cuts from the state legislature!



Salaries: (from numbers jotted down at a meeting)

F-T faculty3.0
Other Staff3.3

These salary numbers include all "overhead" costs, such as Health insurance, Retirement, the employer part of FICA, and some other fringe benefits. The "other staff" category includes many professionals who are not teaching faculty (such as counselors and librarians) as well as all of the worker bees in administration (financial aid, admissions), but also includes the coaches for our athletic teams. The admin category is just upper management, such as deans and directors; people making more than a starting Asst. Professor. As you might deduce, our adjuncts are paid squat, although part of the difference is that they don't get fringe benefits and also don't have any non-teaching assignments like regular faculty do.

A good measure for adjunct pay at our college is that they get about half of what I get for a class taught in the summer or as an "extra" class. Interestingly, this means that the college does not seek the lowest cost alternative for teaching sections not covered by our annual contract. Full time faculty are given the first choice for summer classes and extra classes, not the lower cost adjuncts. If the class is small, as mine was this summer, my salary is barely covered by tuition.

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College Finances - A Proposed Meme

I am a big fan of Dean Dad's blog about the administrative side of a CC. I learn a lot about his job and, indirectly, the challenges my own Dean faces that I don't already know about. However, one thing that bugs me is the absence of some all important context: budgets.

I've challenged him several times to give us an idea of what parameters he has to operate within, but no joy. Others who comment there might also benefit from knowing how their own colleges look in comparison to his. I suspect that he is justifiably concerned that too much information would expose his identity, but I have a solution. Normalize the data, and round some of the numbers to obscure their origin further. Details are below the fold.

Link to your example in the comments. I'll do mine in a separate article, and maybe one or two others for grins.

You must choose one of three categories: Community College (budget normed to 10.0 M$), 4-year College or University (normed to 100 M$), and Research University (normed to 1000 M$).

I know these numbers are unrealistic, since my CC's budget is much bigger than 10 M$ and the University of Michigan is around 2000 M$ without counting their side businesses, but they have the virtue of being easily compared. Besides, I know a small CC that has a budget less than 10 M$ and several mid-sized universities in the 100 M$ range, so they are not complete nonsense.

The selection of the budget numbers themselves can be problematical. For a CC, it should be the entire budget. For universities, it should be the total of the "general revenue" and "research" budgets, so universities would have one extra income category (research grants) and two extra expense categories (research expenditures and overhead). This will illustrate just how "research extensive" your school is. Exclude major items like the 2400 M$ the University of Michigan budgets for its hospital and other businesses (football?) that actually exceed their teaching and research budgets.

Income should include a breakdown for public funds (you can identify the tax base as being state or local if you wish), tuition, and other (which would be mostly grants and gifts at at CC), with a separate research line for a university. Private schools could put endowment income in "other" or single it out. Divide each of these by the total budget to get a percentage, round badly to hide the details, and scale so they add up to the relevant total (10, 100, or 1000 M$).

Side remark:
If you know what the state/tuition ratio was 10 years ago, that would be really interesting. I have not found that info for my school but it is talked about enough that people should have data to back them up.

Expense should show the usual categories of salaries and operations, but please try to get the detailed budget info that breaks salaries down into key categories: administration (any pay grades above that of a new asst. prof?), t-t faculty, adjunct faculty, other support staff, and research faculty if that is relevant. Those can be harder to get, but see if you can give the ratio of f-t to adjunct faculty if you can't get at the salary breakdown.

If you don't know how to build a table, do a "view source" on the example I gave in a followup article and look about 1/3 of the way down into the file for a "table" tag.

If you want to give the number of FTE students (total credits divided by 30) rounded to even thousands to indicate the size of the school, feel free.

Thanks in advance.

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Tuesday, June 24, 2008

Astronomy and Homer's Odyssey

A news release from Rockefeller University reports that a mathematical physicist and an astronomer have just published an article that uses the relative dates of certain astronomical events in Homer's The Odyssey to put a specific date on the return of Odysseus (aka Ulysses) to Ithaca.

The date is 16 April 1178 BCE.

A nice bit of applied physics and astronomy. And now folks who teach the classics have a day they can use like we use Pi Day (aka Talk Like a Physicist Day or Einstein's Birthday) and Mole Day in the sciences.

Hat tip to today's quick takes at IHE.

UPDATE (1 July 2008):
And, according to the BBC, astronomers have also proposed a different date for Julius Caesar's landing in Britain in 55 BCE. In this case it was based on actual observations of tidal currents in August 2007 under astronomical conditions that matched those more than 2000 years earlier. The full story is in Sky & Telescope.

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I'm so old ...

that I remember when MTV only showed music videos. That is what I tell my students, and now I have the fake graph to back it up.

song chart memes
from graphjam, LOLgraphs for the Excel-impaired.

I've also used a 'brick' cell phone and Zip disks, not to mention 8-inch floppies. The former is a good lesson on the importance of mundane technologies such as batteries (for power) and magnets (for speakers) in the miniaturization of every day items. The latter is a good lesson in the impermanence of any data storage solution. Cell phones are also an interesting lesson in the indirect effect of a technology: by driving lithium-ion battery development, they are enabling the next generation of hybrid or electric cars. (If you did not know it, these batteries have only been commercialized in the last 15 years, but are only slightly newer than nickel-metal hydride rechargeable batteries that powered the cool toys of the late 20th century.)

Entertainment offers an interesting window into the history of technology. Movies set in the present day will typically feature product placement of whatever was the hippest, coolest consumer items of that day. Many of my parent's wedding gifts are prominently displayed in movies of that era. The crucial plot element of "Zip Disk" in Zoolander will need explaining to the next generation, just as its use of absurdly small cell phones will probably not be as funny in twenty years.

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Sunday, June 22, 2008

Lab classes

I actually started writing this back in April of 2007 ... see bottom of article for references to the prompting articles and some more recent ones. That put it on my list of things to do looking back at my first year of blogging. Also, if you have not already done so, take a look at the previous article and reply to the poll question about recording lab data.

I think I have a pretty clear idea of the main objectives and how to achieve them in my calc-based physics lectures, but I will resist the temptation to outline them here. However, my feeling for the main objectives of the corresponding first year lab classes is another matter. OK, I think I know what the important ones are, but I can't identify one or two that should be emphasized above all others and it seems impossible to get the students to make all of them a priority. Is it because they have their own idea of what the lab goals are? Do those skills, subtle as they sometimes are, appear too mundane? Is it the challenge of critical thinking? Is it because they look at each lab as something like a science fair project back in elementary school? Or are my priorities wrong?

Side thought:
One way to find out what the students think is to simply ask them that question this fall. (Might even be good to ask them what they think the purpose of the lecture class is!) But right now I am using this question along with my own musings on the subject in the hope it will clarify my view of the lab.

The subject here is the first year physics lab (or chemistry lab), not one of the advanced labs taken by a physics, engineering, or chemistry major. However, I would love to get your short list of things that students don't know when they take a junior-level physics or engineering lab if you have experience teaching one of these. I learned one of those details from a lab TA at a nearby engineering college and have incorporated it into my assessment at several points.


Technical writing will be taken up in a separate article.

So which one or two of the following items do you think is most important, or is there something I left off of my list? Feel free to add any other thoughts you might have.

1. Making the measurements correctly.
I am always surprised how many students don't want to use all of the information available on a ruler yet blame the instrument for their own lack of care. (I'll bet real money that this is why they prefer digital devices despite the fact that all of the same digits are on the analog device.) I think one of the most important objectives is to understand the importance of getting the most out of whatever tools are available.

2. Recording the measurements.
Part of this is the simple skill of writing down the value (in ink) that was measured, but the other part is estimating the uncertainty and using the uncertainty and significant figures to tell someone else how carefully you think the measurement was done. High on the list has to be the basic step of reporting a measured value in a way that clearly indicates its reliability (and its units, of course). Is this something you specifically test on lab exams?

3. Following directions.
Some labs have a rather detailed procedure that needs to be executed step by step if the equipment is to work properly. I'd say that half of the procedural questions I get in the lab are answered in the lab manual, indicating that it has not been read and/or read with comprehension.

4. Design your own experiment.
Our labs are not as "cook book" as those in first semester chemistry, but they leave no room for student creativity -- primarily to avoid major student blunders that would make the work impossible to grade and keep the student from learning anything about the phenomenon being studied. Do any of you do this, or do it as part of a practical lab exam (e.g. design a set of circuit experiments to figure out what is inside this black box)?

5. Critical thinking with uncertainties.
A related, and exceptionally challenging problem, is getting across the idea of what criteria must be met for an experiment to "agree" with a prediction or a known value, or to establish that some effect (e.g friction) is or is not present at a significant level. I think this last one is particularly difficult because so many first-semester lab experiments don't work all that well in the hands of amateurs, so I push it mainly in the second semester.

6. Learn from mistakes.
Probably the most irritating thing to me are the students who make the same kinds of mistakes all year, often as a result of failing to prepare for lab or simply being in a hurry to get out and "get away with" doing the least amount of work possible. Do you ramp up the grading penalties as the semester goes on?

7. Hands on experience with the phenomenon.
Sometimes we want them to simply experience the phenomenon, as a way of reinforcing or illustrating what goes on in lecture. They really like these labs when they are tightly linked to lecture in a "studio physics" style of learning, much more so than a corresponding demonstration in lecture. Should there be more emphasis on this, or would that hurt their preparation for advanced labs in engineering?

8. Respect the limitations of digital meters.
Students (including those in my generation, who did not grow up with calculators) have a near-religious belief in the perfection of any number generated by a digital device. They do not know their calculators use BCD arithmetic with guard digits to hide their inherent flaws from view in trivial calculations. They do not know that calculations done by their computer running a program written in C++ (or any other language) use a different system with different flaws. Thus they think that every digit displayed by a multimeter is 100% reliable, like the mark on a ruler. They don't even suspect that those numbers are actually raw data from an analog physics experiment, so they are stunned when they don't round to the value displayed when you select a different range on the meter. This is one thing that I plan to explore in more detail during our initial lab in physics 2 this year.


Background articles from out in the blog world, mostly circa the spring of 2007 ...

A few of the problems I suspect originate with student perceptions of our labs as an extension of ones done in elementary school or high school could benefit from the kinds of reforms Chad Orzel proposed for the physics-major curriculum, which were centered on the introductory physics class I teach. I also like Chad's succinct rant and more detailed critique of remarks from some silly philosopher who thought labs are not real classes. Not only do I agree with some commenters that labs are more work than "real courses", I insist on teaching a certain lab to be sure students are forced learn certain skills. And I am a theorist, not an experimentalist, thus proving that a theorist is not a philosopher.

I suppose the reason that the Playground Philosopher doesn't like labs is tied into preferring thought to action. But would you prefer to drive over a bridge designed by an engineer who used pure thought to come up with the strength of the steel being used, or one who used a measured value and had done enough measurements to have a gut understanding that there are uncertainties in that measure value, no matter what the data book says?

Other critiques of that philosophical position were written by Dr. Stemwedel Labs and learning science and in Chad Orzel' third article about Labs and Learning. A related thought also appears in Chad's article listing "to plan and carry out a simple experiment" as number 1 on the list of skills every physicist should have.

There were articles by Female Science Professor on using basic methods rather than automation in the lab as well as a related one by Professor Orzel on whether to automate data taking. I find that automation (e.g. some of the PASCO sensor systems) hides what has gone on in the measurement but makes it easy to do a many-part experiment in a practical time frame.

Chad Orzel wrote about reforming intro labs in a comment responding to one of the earlier parts of a 5 series on altering the approach in the intro lab.

I'll also link to a March 2007 by Female Science Professor about 100% men in labs. It's not specifically germane to this particular topic, but I have noticed that it is really important to watch who gets paired up with a female student in the lab. There are way too many guys who lack any clue about what they are doing but possess massive amounts of bluff that convinces their lab partner they know what they are doing. Young men are more immune to this than young women, although anyone who lacks confidence is likely to fall for it. Ideally, I put the clueless guys together and let them bluff each other.

Link forward added:
I wrote more about the subject in this last paragraph in an article published in July 2008.

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Poll: Recording Lab Data

A soon-to-appear article will look at learning objectives in the physics lab, but I wanted to single out one topic for its own poll:

Do your students use a bound lab notebook for all data or do you collect individual lab reports that contain a raw data sheet?

Do you require that students use (or, if your are a student, were you required to use) ink when recording lab data, and how do you punish violators?

We use a data sheet that is handed out in class or taken from the (publisher's) lab manual, and that data sheet is turned in as part of a lab report.

Our syllabus requires that students use ink, but it seems to be rarely enforced by our adjuncts and the students get annoyed when I enforce it. The really sloppy ones hate showing that they used the wrong end of the ruler, and the perfectionists hate having anything mar the neat organization of their papers. Some go so far as to use erasable ink.

I keep trying different tactics to enforce this and will try a new one this fall, but I seek any good ideas you might have (either as a student or as a teacher).

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Friday, June 20, 2008

Basics for Prerequisite?

First, thanks folks.

I want to summarize what I got out of the discussion of my first article seeking a good synonym for prerequisite when advising students placing into pre-college "prep" classes in math or english. (There was also a backstory about the issues encountered in college-level classes, particularly with mathematics in my physics class.)

I found the suggestions quite interesting, although most concerned getting the idea across when teaching a college-level course in english or math or physics rather than motivating kids placing into "prep" classes, either in new student orientation itself or advising students going through orientation. I will summarize these two topics separately.

Teaching college-level courses

Here I think the term BASIC is perfect. It helps get across the idea that the bar has been raised in college. The freshman or sophomore class they are is is just a foundation for what is expected in the next LEVEL class. What might look advanced right now, especially when entering freshman comp or freshman algebra or pre-calc, will be the minimum expected in the future. It might even work in a "prep" class, but it sends a more powerful signal when you talk about the derivative in calculus being a "basic" skill!

While re-reading the previous discussion, it occurred to me that it might be interesting to analyze the word PREREQUISITE in conjunction with the syllabus on the first day of any class, but particularly a comp class. Might even make a good subject for a one paragraph essay the first day. Take it apart into PRE, before, and REQUISITE, required, but then ask what "required before" really means for the classes that have comp I as a pre-req. Is it "mandatory" in the sense that pass-and-forget will still result in a degree, like in high school, or is it a set of MINIMUM SKILLS that must be learned if you are to have any chance of not failing the next class? Could even create an assignment where you ask them to find someone in that next class and ask them if they (fill in the blank with skill, such as writing a big research paper or a lab report, that you already know has to be done in that class).

I already make it a habit to do what Dr. Crazy described, but hearing it from her and k8 reminded me of just how important it is to give students this information on a regular basis. That means it can't be just me and you. It needs to be everyone who teaches my future students algebra or trig (or english composition). And that only works if we give them a list of things that will be used again, and where, so they are all on the same page.

Now I'll tell you why I brought this up. Our math faculty have been working at reforming some of the classes that lead up to calculus. (I think they are finally figuring out that some of the problems seen in calculus or physics are our own creation.) They have gone so far as to start to talk to those of us who teach physics, that is, to the people who have their classes as a prerequisite. With an opportunity like this showing up, I want to make the most of it.

So the follow-up question to anyone who teaches physics or engineering is: What single mistake from algebra or trig most revolts you when you see it made? What should be punished unmercifully in a pre-calculus class?

Motivating under-prepared students

This is a bigger challenge, because the term has to survive on its own the first time a student hears it, without the kind of elaboration or repetition that is possible in a classroom.

OK, maybe it can be explained further during advising, but I am hoping to find a term that reframes the concept away from "required" or "mandatory" (which these kids have learned means nothing, because most classes pick up about halfway through the previous one) and towards "essential minimum knowledge". Our humanities classes don't teach you how to write a research paper, they expect you to Just Do It. Ditto for algebra and trig in our calculus and physics classes.

Maybe referring to those "prep" classes as presenting COLLEGE-LEVEL BASICS, the minimum skills needed to survive in a college english or math class, is the way to go. What do you think? Would that make it easier to explain to a kid that their placement scores are a result of being taught HS-level basics, the minimum needed to pass the HS exit exam, rather than what is needed in college? Might be worth a try.

Any suggestions about how to do a better job of getting this across to the recent grads who place into pre-college math and english classes? I don't mention returning students because it just does not seem to be a problem for them. They know they don't remember anything from high school, or know they weren't taught it. [True story: A student who had graduated high school circa the 1970s had not taken any math beyond 9th grade. She was told it was better if she took chorus, since girls didn't need to know math. She had plenty of motivation when she came back to school to get a business degree a quarter century later, and she succeeded.]

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Ice on Mars - Update

(Followup to an earlier article from the end of May.) NASA is now reporting visual evidence of ice on Mars.

I don't know why some in the media chose the pictures they did, but the best ones among the various pictures available in the JPL Phoenix News photo collection are linked here:

Very striking.

The key phenomenon here is sublimation, where a solid turns directly into a gas without going through a liquid phase. This is what CO2 (carbon dioxide, which is "dry ice" in its solid form below -78 C or 195 K) does on earth, and also how snow "dries out" and becomes extremely light powder in places that have low humdity yet are well below freezing. The reverse process, deposition, is the way that frost forms on a cold surface without any liquid water being involved.

The important data we need to interpret these observations are given in the weather report for Mars. The atmospheric pressure is 8.5 millibars (0.1 psi) while the temperature varies from -80 C (193 K) at night to -30 C (243 K) during the day. At this low pressure, CO2 is a gas across this entire temperature range. (That is why the polar "dry ice" cap has vanished in this location during the Martian summer.) If the white material was dry ice, it would rapidly turn to gas between when the trench was dug and when the photo was taken. If it is salt, it would not sublime. The best candidate is water. Water is a solid at these temperatures and would sublimate slowly, just like when clothes are hung out to dry in the winter.

News stories:
The best article is in the New Scientist. The BBC has a good story on this, as does MSNBC (with a good picture choice), while CNN only blogs it with an irrelevant photo of the sampler to illustrate nothing.

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Wednesday, June 18, 2008

Early Computer Music

An article from the BBC reports on the oldest recording of computer music, played by a commercial version of the Manchester Mark I computer (read a more technical article here, which includes links to articles about the 50th anniversary and construction of a working replica).

The vintage BBC video of the original "baby" machine in 1948 is priceless!

I love that the program to check if 2127 - 1 (a Mersenne number) is a prime number (it is, as first proved in 1876) took 25 minutes to run.

I also like the image of a computer program written in machine language. That brings back some memories! And a question: Does The Thomas still have a MISTIC simulator? If so, I have a program for it ... somewhere.

There is another anniversary story from the BBC, on 20 June, that has some additional information and another photo of the computer. I had forgotten that it had 128 bytes of memory. (That is not a misprint: 128 bytes, not 128 kilobytes like the earliest PC had. That factor of 1000, actually 1024 if you want to be picky, really limits what you can do when writing a program.)

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Tuesday, June 17, 2008

Synonym for Prerequisite?

I've put the background information below the fold so I can keep the question up front.

Today's question is whether many of our most at risk students, the ones who struggle because they don't have the prerequisites to succeed in college level classes, don't understand what we are talking to them about because the word we use, prerequisite, has four syllables? Does a typical CC student who placed into a pre-college reading and writing class understand this word? I doubt it, but maybe someone who teaches english will wander in here and offer some advice.

Can anyone suggest a clear, simple phrase that gets the idea of "prerequisite" across using a middle school vocabulary?

The idea we must get across is that we expect them to retain what is taught in the class, not just cram to get past the next test. To learn it so they can apply it in the next class, because they will have to write or do basic algebra in their next class and the next one and the next one.

The Backstory

If you have read my blog much at all, you know that student comprehension of the idea of a prerequisite is a pet peeve of mine. It even rates its own blog category. Students generally don't get the idea of actually learning a subject for future use, so they often "take" a class with the apparent objective of forgetting it all as soon as they earn their C. For the better students, this might even work in a range of classes from high school through some of the general education classes, but they often run into trouble when they need to actually know trig and the rules of logarithms to succeed in calculus or physics.

But I'm not writing about that today. I'm writing about the ones who are struggling in pre-college "prep" classes because they never learned reading or english or how to work with symbols in the most basic algebra class but somehow managed to pass the high school exit exam or the GED. They also are the most resistant to the idea that they need to learn (not just pass) the material in their prep classes. [Older, returning students seem to understand the need for prep classes because they are under no illusions about remembering anything from high school. In contrast, recent high school grads seem to operate under a large number of illusions about what they learned in high school. The vast majority believe some myth about "not testing well" as the explanation for why they can't do fractions or solve an equation.]

This is a serious problem, and using a ten dollar college word for it only helps in discussions amongst professionals. We need a better way to talk about this to students.

Some Synonyms

NECESSARY before you can do something else

REQUIRED prior to taking the next class, REQUIREMENT




Some of these don't work when used with "course", since students seem to associate that with getting past the class rather than learning the material. Maybe the important thing is to talk about skills rather than the class. Would it make that recent grad more comfortable if we said they lack specific skills needed in college classes rather than imply they lack skills, period? I have no clue, but this is something to think about.

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Saturday, June 14, 2008

Hamilton, Lagrange, or Newton?

Matt offers a nice toy problem solved with Lagrangian methods. (Luckily, he got it right despite posting on Friday the 13th.)

So which approach is inherently cooler, Hamilton's, Lagrange's, or Newton's?

Is it Hamilton's mechanics, because it introduces the symbol p for the generalized momentum conjugate to the generalized coordinate q, because it provides the neatest formal connection to non-relativistic quantum mechanics, or because you get to say "symplectic" once in awhile? Is it Lagrange's mechanics, because it is based on the very important ideas of the calculus of variations, because it is used in relativistic quantum mechanics, or because it knows where the "action" is? Or is it Newton's mechanics, because things should be pushed around by forces, or because his work started it all?

According to Hamilton, it is Lagrange.

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Predictable Grades

Profgrrrl blogged about being able to predict where her summer (grad) students would fall on the grad distribution for a test about 2/3 of the way through a short semester. In the comments, Belle (who had a wonderful recent article about nonsense in some AP history? exams on the grading table) asked how that might be done.

I think Profgrrrrl's observation was about the sort of informal approach many of us do, where we have learned to expect some continuity in both "A" and "D" performance throughout the semester, but I've gone a bit further as a teaching tool.

In one gen-ed class, I make a point of recording the quasi-midterm percentage grade I report to them after one of the exams. I put it in a place in my gradebook where I can easily compare it to the final grade, pretty much at a glance. It is useful to know that most students who are borderline (particularly on the pass line) improve their grade on the final exam - mostly because the first exam is harder than they expect, but they can get those kinds of questions right on the final if they change how they study for the class. I can use that to encourage them to keep improving.

In my first semester physics class, I have been doing a retrospective study for a number of years, building a histogram of sorts where I put the final grade in the class next to the numerical score on the first hour exam. A pattern emerges where most bad scores fail and most good scores do well, but there are always a few cases where a 100 gets an F or a 40 gets a B. (The latter is possible because I follow one of many standard grading schemes where the worst exam is either dropped or replaced by the score on the final exam. The former is possible because some students don't keep doing what got them the good grade on the first test.) The extremes tend to track pretty well.

The interesting result is that the most critical group of students are the ones in the C-D range. For them, what matters the most is what they do about their performance on the first test. Do they sit down and work it all out correctly the very next night? Do they figure out the relationship between exam questions and key topics covered in the homework and adjust their study methods accordingly? Do they realize that copying an example in the book or getting someone else to tell them what formula to use to get the homework correct is not quite the same as "doing" the homework with the goal of "learning" how to do problems on a test? If they do, their grades generally go up into the B-C range, sometimes even into the A range. If they don't, their grades generally go down into the D-F range. A person with a 70 on that first exam is almost literally sitting on the Continental Divide of performance, sliding down the razor blade of life.

Again, conveying this sort of information can make the act of returning the first exam into a teachable moment. Not that all of them pay attention or choose to put in the effort needed to learn, but enough clearly do that I find it to be a useful effort on my part.

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Thursday, June 12, 2008

Thought Provoking Reading

Two really good articles from IHE:

I've barely had time to read these, let alone think hard about them, but each one touch es on an issue that is critical at my CC and probably at every college or university in the country.

But I think they are both more important at a CC.

I see a lot of vets in my classes, and many of them are among my top students. But some of them face adjustment problems, and some are still in the reserve or guard with on-going time commitments that can interfere with their studies. But none of my students face the challenges of one vet who was in a colleague's class that met just before mine a year or so ago: a triple amputee. That brings the war home. Most of the vets in my classes don't stand out because older students are quite common here, but they quickly stand out because of their work ethic and leadership skills. Clearly the people behind the program at Montgomery College (Maryland) saw many of the same things:

First, the overwhelming emphasis within Combat2College is on identifying how military experience and training are positive assets that can be channeled toward the formation of attitudes and behaviors to promote success in college. Second, the program does not emphasize post-traumatic stress disorder, traumatic brain injury and other disorders experienced by veterans of the ongoing wars. It is realistic and truthful, and notes that these are problems experienced by some veterans, and provides information regarding referral resources and positive coping skills. However, the primary focus is on assisting the veteran to explore and identify the aspects of military training and combat experience that promote personal strength and psychological resilience, and how these can be channeled toward success in college.

Focus groups with combat veterans who had already enrolled in college revealed a common theme of distress and discomfort until “connecting” with other veterans on campus.

I love the idea of building a vet learning community, because I have seen these students do some of that on their own. (It never ceases to amaze me how former Marines find each other.) They are used to working as part of a team, and would probably be more likely than our regular students to see the value in investing time in that sort of effort, an effort that much research (and my own experience) says always pays off in improved learning.

I suspect we get more than our share of these students because we are very welcoming to part time and returning students, but our support systems are nowhere near as robust as those described in the article above. I'm sure we will get a lot more if the long-overdue improved GI Bill gets passed by Congress and signed by this President ... or the next one. That makes a concerted approach all the more important.

Female faculty:
Our faculty is about half female, which makes some of the issues raised by the study reported in IHE (which was done at a research university, UC Irvine) quite important, but one thing I did not notice in the article (or maybe just missed) is the difference in how students treat male and female faculty who do the same thing in the classroom. I know I learned a lot about that after forwarding a blog on that subject (might have been from profgrrrl, or maybe Bitch Phd or Dr Crazy) to some of my colleagues and getting an earful about their experiences.

Among other things, I learned that it is not enough to be a supporter of feminism in academia. What I might think is well-meaning advice, because it works for a guy, can be heard very differently when a woman knows it does not work for her. But once that is out of the way, it does help to communicate that support. (There is no other way that someone can learn I am supportive of their contribution to the college, since that isn't something that comes up in day-to-day interactions. It opened up some very valuable communication channels that now extend to mutual classroom observations that cross disciplinary boundaries.)

One item really made me think. We have quite a few women in management positions (pretty natural when half the faculty are women), but I had never really thought about whether that job gets devalued as a result. I don't think so, but the management style of my department chair is so different from that of men in a similar job that a comparison is almost impossible. I can see how a difference in style could lead to a perception of a difference in authority.

I guess its the "quiet" as much as the desperation that bugs me. Discussing those issues might reduce the desperation, since I'd guess that some of those issues bug men as much as women. Neither group will realize what irritants they share if it doesn't get talked about, and the lack of discussion will lead to desperation.

And that is where I celebrate many of the blogs that explore this subject, using anonymity to speak truth without fear of reprisal at work. I have learned a lot from the openness of some of the names in my blogroll, and that has had a positive effect on my ability to communicate with my colleagues.

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Trump Hair

Check this out

I had no idea that there was a sophisticated architectural engineering problem behind the creation of his rather unique "look".

Hat tip to The Thomas.

Actually, what The Donald needs is a hat!

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Wednesday, June 11, 2008


I've gone a bit too long commenting rather than authoring, so its time to write about what a professor can learn from the Rolling Stones.

We saw "Shine a Light" (2008) some time ago on IMAX. (I'll put review notes down below the fold.) FYI, this is a combination documentary and concert film, with the bulk of it devoted to brilliantly edited film of a live performance in NYC (and possibly elsewhere). They open the set with "Jumpin' Jack Flash" (1968), and I couldn't help notice the wide smile on Keith Richards' face at one point during this joyous song.

That's when it hit me: He's played this song countless times for almost 40 years, and it looks like he is having as much fun as he did the first time. No, he is having as much fun as the first time.

And that is what I try to do every day in the classroom: put as much into it as I did when it was all fresh and new.

I've taught exactly the same topic (let's say, projectile motion) lots of times, but not nearly as many times as Richards has played Jumpin' Jack Flash. If he can do it, so can I.

I shared this observation with one of our younger faculty, one who brings Jagger-like intensity and enthusiasm to the classroom. She teaches several sections of the same gen-ed class every semester, and I can tell that the frustrations of some of our students are getting to her (as they sometimes get to me). It hit home, so I am sharing it with you. We have to remember that each semester's crop of students is new (OK, most of them are new) and they have never seen us Live and In Concert. They deserve the same fresh new show, but new and improved with the riffs added as we learn more about how to teach certain parts of it and improvise in front of a live and (sometimes) responsive crowd.

Review notes:

I think it is safe to say that Martin Scorsese is in total control when he directs a movie. Except for this one. You can see the frustration on his part during the initial documentary part of the film, when he is begging for information about the song list for the set and not getting it until the band settles on it just before going on stage.

To see the organization of the stage come out of the chaos of preparation really makes it clear just how professional these guys are.

When I say you can't help notice the smile on Keith Richards' face, that is because his face is 30 feet tall on the screen. It would take a major geological expedition to find your way down into those wrinkles.

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Friday, June 6, 2008

Time and Cosmology

I got a nice heads up from the BBC RSS feed today, which had a story Hints of 'time before Big Bang' today that cited Sean Carrol, who blogs at Cosmic Variance. That led me to a post of his on the same general subject of the Arrow of Time as an advert for his article in Scientific American.

From the BBC article, which is reporting on work submitted Physical Review Letters and presented at the American Astronomical Society this past week, we see that: Their model suggests that new universes could be created spontaneously from apparently empty space. And that this 'cold' empty space would result in an ordered initial state for the universe, so that the Second Law of Thermodynamics will then necessarily produce an Arrow of Time.

Ooh, lots of German Capitalized Words in that paragraph.

Anyway, their argument is based on attributing a systematic variation of the CMB across the sky to a non-uniformity in the space of some other universe that gave rise to our universe as a bubble ... in someone's LHC or RHIC?

I don't have anything to add on the physics since this is well outside the limits of my knowledge of GR and cosmology. This is just posted as a heads up to anyone who happens to read my blog, but I will remark that Chicago's loss was Caltech's gain.

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Thursday, June 5, 2008

Jobs - Part I update

The first article in my series on jobs, mainly faculty jobs, in physics put its focus on the supply side of the job situation. My main objective was to show the origin of a weakly-damped cyclic pattern that started when the pre-Boomer generation earned PhD degrees in massive numbers and filled up the faculty positions needed to teach all of us Baby Boomers going to college. [Boomers are under-represented on most university physics faculties as a result.]

By an odd coincidence, a retirement party for two professors who were hired in the mid 60s led to the discovery of the advertisement shown below. This captures quite well the anger of pre-Boomers who got to the hiring party a year or two too late. Details and comments are below the fold.

This ad came from Physics Today. Based on what else was with it, I would guess it might have been published circa 1978 but I have not gone to a library to track it down. (It could be that it was published as early as 1976 and I just happened to look it up in 1978 or 1979.) If you go looking, it would be at the very end of the classified ads. In addition, a search through the annual index for letters to Physics Today by Robert Yaes, or through the Bulletin of the APS for abstracts he submitted, would turn up a lot more of the same.

Yeah, this guy was bitter. I have to wonder if he messed up and took a post-doc in 1967, planning to look for a job in 1969 only to find that they were all gone. Little did he know that the market was going away in 1967 and would only get worse. And he was not alone in his anger. It is a common theme when I have run into pre-Boomer grads of the same program at my Enormous State Graduate University, ones who finished grad school circa 1970. One, in particular, had a long and lucrative career with IBM (basically straight out of grad school) but is still bitter that his outstanding research work meant nothing once slots had been filled by people who never amounted to much but had one advantage: they graduated 3 or 4 years earlier.

And there is another side effect. When contacting people to have a lab reunion built around this retirement party, I could not help but notice who they found (and collected on their alumni list) and who they did not find - or maybe even try to find. The only PhD grads from my Boomer generation who are listed are ones who happened to be somewhere in academia. They just ignored all of the ones who are off in the real world (even ones at national labs), including ones who have done extremely well (key patents, that sort of thing). If a student does not end up in academia, they don't know what that person ended up doing.

This has important consequences for students even today. As I noted at several points in both part 2 and part 3 of this series, it is quite common for faculty today to know nothing about the two thirds of physics jobs that are outside academia: they don't know where those jobs are, what skills they require, nothing. It was also common when I was a grad student, although some (like my adviser) had kept in touch with all of their students and knew what kinds of jobs they had and how they were (or were not) using their physics skills in that profession.

PS - Yes, they were hired in the mid 60s. The guys who are retiring were on the faculty for over 40 years. I gave another example early in part 2 of the series. Those "retirement replacements" people expected in the 1990s are slowly appearing now, but it is far from clear if all of those lines will remain in physics departments. Budgets are being cut, research priorities are shifting, and the Boomer Echo will be ending in another 5 or 10 years ... and t-t faculty have to be paid for forty years, whether students are there in large numbers or not.

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When Hope Almost Died

Today is the 40th anniversary of the assassination of Bobby Kennedy. [Nit pick: Only because we don't really act as if a new day starts at midnight.] I don't remember the day (the news arrived the next day since he was shot around 3 AM on June 6 according to our clock) because my memory is of him and what he represented, and of the time I shook his hand.

Although the program on CBS tonight, featuring Jeff Greenfield's memories of RFK, brought back those memories, they really came flooding back to me two days ago during Obama's victory speech in Minnesota. It was too much like California in 1968, and one blond college kid reaching over the crowd to get his hand shaken was much too much like my experience a few months earlier.

But the hope you might feel, particularly if you are a youngish Obama supporter who is really involved in politics for the first time, is only half of what got dashed in 1968.

There is no draft today, keeping a half-million man army in a war zone for their 365 day tour-de-Vietnam. Although 50,000 deaths over the many years of that war are a fraction of the losses during the US Civil War and pale in comparison to what happened in Europe during WW I (comparable to the number of soldiers killed at Ypres in WW I whose remains were never identified), they dwarf our losses in Iraq and were quite an immediate threat to my generation. [And if you also knew, as I did, that we had once been Ho Chi Minh's ally against the Japanese and their French colonial collaborators, the pointlessness of the war made it even more disturbing. At the time, I was a long way away from being draft eligible.]

But there was much more. The civil rights movement was also in the middle of the fight to turn the 1965 law into something more than words that would be ignored like those in the 13th, 14th, and 15th amendments were ignored once Reconstruction ended. MLK had just been assassinated, and it was far from clear if the country would ever come close to where it is today - and it still has a long way to go today. Finally, there was the very real risk of nuclear annihilation. There were many times as many nuclear weapons pointed at the US than as are threatening us today, and we had come within one airstrike in Cuba or a nervous fighter pilot in Russia from going up in radioactive smoke in 1962.

RFK brought real hope. His speeches were more than rhetoric. He did not pander to his supporters, arguing against college draft deferments when speaking at a university. He opposed Johnson's plantation-style welfare programs that broke up families, programs that Nixon expanded along with expanding Medicare and other parts of the Great Society that benefited the middle class. That hope died 40 years ago today. And you can't tell me that this wasn't on the minds of the Secret Service detail in Minnesota on Tuesday night.

What came next led to forty years in the wilderness for the Democratic party. Chicago in August. Anti-war Democrats for Nixon, suckered into his secret plan for peace (best kept secret, since the plan was for more war) by foolishly viewing HHH as a pro-war puppet of LBJ. The same nonsense we hear today when pro-Hillary feminists shout racist attacks on Obama and argue for supporting a man who plans to ban abortion and thinks a wife's place is at home writing checks on her beer fortune to look pretty on his arm.

Obama is no RFK, but he offers a similar message to look ahead to the future while abandoning the politics that uses innuendo to fuel hate that can be used to get people to vote against their best interests and keep the oligarchy (now in the guise of preppie John Simpson McCain III) in power. Only time will tell if he will succeed where RFK failed.

Note added:
Campbell Brown wrote an essay about parallels between 1968 and 2008 on 6 June that was impressive only in how shallow it was. Wow, she spent a few hours looking over video footage and still photos of 40 years ago this weekend, June 1968. A few hours? No wonder the press is so easily bamboozled into working from selective leaks and talking points. She might have talked to someone who was alive then, or prehaps just imagined how she would have felt if she had woken up on Wednesday to learn that Sen. Obama had been assassinated as he left the arena in Minnesota and her son was old enough to be drafted to fight in Iraq.

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Tuesday, June 3, 2008

Michigan Delegate Decision

I have lost a lot of respect for Harold Ickes and the Clinton campaign after they started down the Karl Rove path of using coded racial language (I have a colleague who does a first rate job of translating for me when I don't pick up the more subtle ones) and half truths to raise the ire of their supporters.

The latest would be when Ickes said of the DNC Rules committee "This body of 30 individuals has decided that they're going to substitute their judgment for 600,000 voters." This is utter nonsense. In Michigan, 261,833 people explicitly voted against Hillary Clinton and 328,151 people explicitly voted for her.

It would be ignoring the will of the people to use political maneuvers in the Michigan party to transfer some of those votes to Clinton.

Yes, the decision they made disenfranchised 21,000 Kucinich voters and any Edwards supporters who joined Obama supporters in voting "uncommitted", but making the assertion Ickes makes is ignoring three salient facts.

1) Obama supporters made many public appeals for their supporters to turn out and vote "uncommitted", and no other state had anything like the uncommitted vote that was seen in Michigan after Obama respected party rules and pulled his name off of the ballot.

2) Hilary carried Wayne County (Detroit) by 50-46% with only 160,000 people voting in the biggest city in the state, and lost Washtenaw County (Ann Arbor) by 47-44%.

3) More Republicans voted than Democrats, in a state with a Democratic governor and Senators.

These suggest that many Democrats stayed home, that many of those were black, and that the uncommitted votes were all votes against Clinton. How Ickes can conclude that the wishes of 238,000 people would be respected by giving those uncommitted votes to someone who might vote for Clinton has never been explained.

Without a reasoned explanation, and none has been supplied, his assertion has to be seen as pure Rovian hyperbole meant to incite the kind of anti-democratic riot that Rove and friends used to stop the Florida recount before Bush could be shown to be the loser.

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Sunday, June 1, 2008

Congratulations Profgrrrrl and 402!

For the past year, part of the blog world has been following Profgrrrrl's romance with Dr. 402. Saturday, they got engaged.

If you read this, drop on over there and join Mrs Pion and I (and 70+ others) in wishing them the best of luck in their life together, and apart - for this is a Distance Loving relationship.

In physics, the two-body problem is solvable while the three-body problem is usually described as "interesting". [Translation: It can be solved, but it might take forever to do it. BTW, this Wiki article is extremely good.] In the (formerly?) sexist world of physics, talks on this subject generally included an allusion to a mistress, or jokes about taking a mistress as an excuse to explain absences that were actually spent in the lab trying to solve the 3-body problem.

In academia, the two-body problem poses all sorts of challenges. It is bad enough when both people are grad students. (A grad school buddy was the trailing spouse in a time of difficult job prospects, so I know what that can look like.) It must be particularly difficult when both are tenured faculty, as in this case, but they have the advantage of being in a Distance Loving relationship from the start - and using a variety of high tech DL tools (on-line teaching being one of PG's specialties) to maintain it during the courtship phase. My advice to Dr. 402 is to treat Profgrrrrl the same way every day that he has since he met her. And vice versa. And I wish you both luck, and maybe a favorable job jump for one of you, if you plan to add a third body to the equation.

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