Exam Pre-Mortem

Continuing my “disaster” reading the past week, I finished Meltdown over the weekend. Like common popular books published in the past decade, it’s a light and quick read, styled with the usual vignettes adored by journalist-types, with a smattering of self-help. I prefer the heavier, more theory-laden, analysis – hence my choice of reading Normal Accidents before Meltdown. The latter draws quite heavily from the former, making my read quicker, however it has thought-provoking moments. One of these is the Pre-Mortem.

We’re more familiar with the post-mortem – dissecting what went wrong after the bad event. The pre-mortem attempts the analysis before, rather than after, things go poorly. The example in Meltdown was asking students at a business school what can be improved, but the experimental design cleverly had two different prompts. One was the typical “what do you think can be improved?” (more elegantly phrased than my paraphrase) and generated the range of standard student views one might see on such evaluations. The other prompt asked the students to imagine they were alumni two years after graduation, learning that the business school was doing poorly and suffering in reputation. The question was to imagine: “What went wrong?” Essentially, a pre-mortem.

As you might have guessed, responses to the pre-mortem question showed larger variation in scope and increased depth of analysis. Some ideas were more far-fetched, but interesting to consider nevertheless, especially if you were doing some risk-analysis planning. A number of years back, when I was faced with a very difficult and significant life-career decision, I did a pre-mortem – except I didn’t recognize it as such at the time. It was not the only part of my analysis (some forecasting was required), but it was an important piece. For a couple of years after, I regularly debated with myself as to the wisdom of my choice, but I can now look back and see that it was the right thing to do at that juncture. As a planner-administrator, I still regularly do forecasts and analysis, however Meltdown reminded me that I should employ the pre-mortem more often.

As a first step, I wonder if I can use the pre-mortem to help my students. Here’s the setup I’m thinking for a pre-exam writing assignment. “Imagine you just got back your exam and you earned a D. You were both surprised and disappointed. Looking back through your exam and your preparation, what went wrong? Discuss whatever comes to mind.”

Would this help the students better prepare for exams? I hope so. I already have “how to study for this class” tips on my syllabi (including ones from previous students), and I’ve built in some formative assessment approaches to prepare students. I’ve now taught a full year of G-Chem where the students used take-home exams with post-exam self-annotation. In P-Chem, I’ve encouraged group study and exam question forecasting, and tried to help the students annotate their problem sets with some “what went wrong” self-reflection. However, these are all post-mortems.

I’d like to think that the post-mortem on the first exam (if a student does poorly) helps in preparing for the second exam. (My classes typically have 3 or 4 exams before the Final Exam, so the first exam shows up quite early in the semester.) But upon reflection, I’m not so sure. There are students who do well on the first exam but then bomb the second (for a variety of reasons, overconfidence being one). There are students who come by my office asking how they can do better on the next exam; I typically turn the question around and ask the student to reflect. And there are students who don’t darken the door of my office, some proportion of whom probably do zero post-mortem on a previous exam. I also hear students in the hallways talking about getting back exams (from other classes), and the reflection is often shallow to non-existent.

So I hope the pre-mortem will help. Maybe I should do it more than once. Maybe it will also help avoid a meltdown. One can only hope.

Complexity, Coupling, Catastrophe

Watching different countries and governments respond to the Covid pandemic has motivated me to (morbidly) read more about disasters. To see how humankind dealt with the unknown unknowns of epidemics or pandemics, I recommend The Pandemic Century: One Hundred Years of Panic, Hysteria, and Hubris. Published in 2019, the author Mark Honigsbaum takes you on a case-study-style tour from the Spanish Flu to Zika (with “parrot fever” in between). The chapter on SARS is particularly interesting, given the present crisis – the same hysteria and hubris echo strongly. Are we learning the lessons of history? Or are we simply being human?

But that’s not the book I want to discuss in today’s post. While breezing through Pandemic Century, I’m also slowly working my way through Normal Accidents by Charles Perrow. The title is misleading, given the impetus for this 1984 book was the analysis of the Three Mile Island nuclear power plant “disaster”, it’s anything but normal. Perrow explains that “normal” here means “inherent to the system”, and that this is an ever-present danger in interactively complex and tightly coupled systems. Things will go wrong. It’s not a question of if but when.

Perrow is a sociologist who studies organizations. I’ve dabbled in this literature as part of my interest in complex systems. Sure enough, garbage can theory makes its appearance, but my focus today is on Complexity and Coupling, two key factors Perrow introduces in his analyses. The title of today’s post comes from the title to Chapter 3 in Normal Accidents.

Complex interactions have numerous subsystem linkages, some seen some unforeseen, multiple paths, feedback loops, and “connections… multiply as other parts or units or subsystems are reached”. They are distinguished from linear interactions (serial, one thing after another), but they are not labeled non-linear, because there are non-linear systems that are comprehensible. Complex systems, according to Perrow, have hidden interactions reducing their comprehensibility. He argues that this is particularly true of processes involving “transformation”, i.e., they “can be described, but not really understood”. He groups nuclear power production, chemical plants, and recombinant DNA technology in this category. Interestingly, these are all underlying processes where you can’t quite “see” what is going on.

Systems can be coupled tightly or loosely. Tightly coupled systems can respond quickly to changes in lockstep; they tend to be classified as more efficient. Loosely coupled systems, on the other hand, “allows certain parts of the system to express themselves according to their own logic or interest” but are more robust to recovery if something breaks. Perrow goes into detail with many examples of what it means to be tightly or loosely coupled not just from an engineering perspective but also from human organizations.   

Besides nuclear power, Perrow analyzes several systems of interest to explore the landscape of complexity and coupling. These include petrochemical plants, aircraft design and air-traffic control, marine accidents, dam and mine accidents, outer space exploration, and recombinant DNA technology. He then places these, and other systems, along a two-axis chart as shown below.

Universities are in the bottom right quadrant. They are interactively complex, but very loosely coupled. Or at least that’s how Perrow views them in 1984. (You can also see trade schools and junior colleges on the chart.) That seems fair. Universities have, in Clark Kerr’s words, become “multiversities”. There are many stakeholders, seemingly divergent goals, and seemingly slow-to-change behemoths. Traditional universities are not known for their nimbleness. In 2020, there is even more multi to the multiversity. The entrance of educational upstarts into an increasingly competitive space has brought about higher education’s own hubris and hysteria. As the “crisis” heightens, university administrations increasingly insist on more centralization to avert seemingly looming disasters. Covid-19 will accelerate the trend towards the All-Administrative University. Never let a good crisis go to waste.

Perrow’s primary polemic is highlighting the serious dangers of nuclear power plants and weaponry, from the technical but also the organizational point of view. These sit in the top right corner of his chart. It has to do with how these systems could and perhaps should organize themselves to deal with the inevitable crises, black swan events notwithstanding. Should these organizations centralize or decentralize? That is the question! Let’s take each of the quadrants in turn.

TOP LEFT: In interactively linear and tightly coupled systems such as dams, power grids, and rail transport, centralization is recommended. You want maximum efficiency out of these systems, and tight-coupling helps with that. Also since the system is not complex, it is possible to respond quickly and concertedly through being centralized. Basically, you want centralization for tight-coupling, and centralization is “compatible” with non-complex systems.

BOTTOM RIGHT: Let’s look at the opposite quadrant, applicable to mining, university, R&D. When you have an interactively complex system, Perrow argues (with the many examples in his book) that decentralization is desirable. When problems crop up, it’s often advantageous to have frontline people (preferably with experience and expertise) be highly involved and empowered to come up with solutions. Loose coupling allows for this, and information can move back and forth between operators and management without severe time crunch constraints.

TOP RIGHT: The problem in this quadrant is that centralization is needed to cope with tight coupling. But interactively complex systems are better solved through decentralized approaches. Thus, neither approach is optimal and Perrow predicts that the organizations of these systems will ping-pong back and forth with a mixture of approaches that will constantly evolve depending on what disaster hits. Organizational structure thus varies reactively.

BOTTOM LEFT: Since the interactions are not complex, and they are loosely coupled, it doesn’t matter which you choose – both centralization and decentralization are compatible. Perrow notes however that “elites” (the bosses) tend to favor centralization over decentralization in most cases. That’s no surprise. One theme that Perrow emphasizes as a sociologist is power relations within the system.

In my recent post on collegiality, my bias towards decentralized “organic” subunits within the university system is apparent. As a mid-level administrator, one of my tasks was to fend off higher-administration from its tendency to recommend centralized solutions in a one-size-fits-all approach. Financial fears have made these tendencies more acute. Administrators want more tight coupling. At the same time administration is increasing in scope and manpower with increasing interactive complexity of the multiversity. This combination will move universities towards the upper right quadrant. More fail-safe systems must be put in place, further increasing interactive complexity. It’s a positive feedback loop.

Even if we were not in Covid crisis, and the university isn’t like a nuclear power plant with catastrophic potential, the move towards increasing centralization and top-down approaches is very worrying. And it’s all in the name of supposedly running leaner, better, more efficient, whatever. Humans are involved. I close by quoting Perrow.

Organizational theorists have long since given up hope of finding perfect or even exceedingly well-run organizations, even where there is no catastrophic potential. It is an enduring limitation – if it is a limitation – of our human condition. It means that humans do not exist to give their all to organizations run by someone else, and that organizations inevitably will be run, to some degree, contrary to their interests. This is why it is not a problem of capitalism; socialist countries, and even the ideal communist system, cannot escape the dilemmas of cooperative, organizational effort on any substantial scale and with any substantial complexity and uncertainty. At some point the cost of extracting obedience exceeds the benefits of organized activity.

P.S. As one studying the origin-of-life, I've also been reflecting on the interplay of complexity and coupling as I learn biochemistry! More about that in a future post.

Confronting the Unknown

Why do universities have professors?

Um… to teach students, maybe. And to extend knowledge in some area, isn’t that research…?

If that is so, what criteria makes one a professor?

I would argue: (1) Subject-matter expertise; (2) the ability to help novices gain some expertise in the area; and (3) engaging with ideas at the forefront of our disciplines and thereby possibly extending knowledge. In today’s post, I’d like to delve into these three points and explore some possible synergies.

Note that one doesn’t need to be employed by a university to cover the criteria above. You could be an independent itinerant scholar-professor; although for many of us, being employed by a university brings us into a vibrant community and helps pay the bills.

First, how does one define (or distinguish) the novice from the expert? Is it about being less ignorant and knowing more stuff? I suppose. But I think quantity of knowledge is less useful as a measure. I might know lots of trivial facts; good for Jeopardy perhaps, but have little expertise. Novice students, with some cramming, can spout a veritable fountain of information and spill much ink on to an exam – and still demonstrate little to no expertise.

A more useful indicator of expertise is how one confronts the unknown. What do you do when you come up with a puzzle in your discipline? How do you reason your way through the problem-solving process? I argue that this is how expertise is revealed. The novice clutches at straws, is scattershot in approach, has difficulty evaluating the relative strength of different arguments, and very quickly runs out of productive ideas. If not willing to admit ignorance, the novice is too quick to proclaim a definitive answer. The expert, on the other hand, sieves the good from the bad, marshals a range of arguments with associated probabilities, and is able to provide a complex but coherent (possibly partial) solution towards the answer, without proclaiming it solved.

The periodic table is full of such puzzles if you examine it closely. One teaser for my general chemistry students is explaining the anomalously weak bond of F₂. For my physical chemistry students, given that the the two-electron H₂ bond is stronger than its one-electron counterpart H₂⁺, why is the opposite observed for Li₂ and Li₂⁺? For inorganic chemistry, why are the ground state valence electron configurations for Ni, Pd, and Pt, different?

Second, how do we as professors move novices on the road to expertise? By growing the knowledge of our students? I would argue, yes, but I think we should also grow their ignorance – and thereby teach them how to critically confront the unknown. I think that superficial learning may increase knowledge while lessening ignorance, but that in deeper learning, both knowledge and ignorance grow together. It’s not just the recognition of ignorance; a student who does poorly on an exam recognizes his or her ignorance upon getting back the exam and seeing the low score. Rather it’s the recognition of increased uncertainty as one wades into complexity and delves deeper into knowledge. Assumptions are questioned and interrogated. Probabilities begin to mount as certainties fade.

The author Arnold Wentzel in his book Teaching Complex Ideas has a chapter titled: “If you want students to reason like experts, don’t teach them how to reason.” He draws from educational psychology research, but the underlying principle is that the art (or skill) of general reasoning is a primary biological trait, as argued by Geary. What’s important is to provide the conditions for reasoning, and this requires disciplinary-based knowledge – something that must be learned – and engaging in the back-and-forth of argument and counterargument based on this knowledge and its limits (ignorance). This underscores the importance of “teaching” critical thinking within the context of one’s discipline. There is little evidence for the overall utility and effectiveness of teaching un-anchored generalized “critical thinking” skills – unfortunately a present fad that I hope runs its course soon.

Third, and perhaps unsurprising, is that as professors pushing the boundaries of knowledge we are directly engaged in confronting the unknown. There’s an impression that professors focus on some esoteric figment of knowledge that’s useless to society at large; the academy needs to counteract this view by continually engaging the broad areas in each of our disciplines. We should be doing this in our teaching and in our public service to the university and beyond; the warped incentive structure of academia notwithstanding (that we should combat). We should take advantage of teaching to immerse both ourselves and our students in the fundamental nature of our subject matter. Teaching and learning blur, as both professors and students learn together – at different levels perhaps, but still learning.

When I first started out as a professor, teaching and research felt like two separate spheres. Class felt like the place where I conveyed information to students that was familiar to me, but not to them. I was moving them from ignorance to knowledge. My research seemed to have little connection to my classes, other than providing timely real-world examples here and there. Today, I work less on the “productive” parts of my research (usually measured in peer-review articles) and spend more time thinking about both deeper and broader questions in my area, which spill over more into my classes. My reading has broadened, and my excitement for learning new things has increased! I hope to instill this in my students, although I’m not sure if I’m doing this coherently. Sometimes it feels like grasping in the dark, confronting the unknown. Paradoxically, I might be on to something!

Collegiality

Last week, InsideHigherEd had an article titled “Annual Collegiality Reviews?” Several institutions have attempted to introduce the category into annual faculty performance reviews. The American Association of University Professors (AAUP) strongly advises against this. But what exactly is collegiality? It can be a slippery concept, hard to define. “I know it when I see it” does not constitute an adequate definition.

According to Wikipedia, the root word for college is to be “selected together”. Thus, colleagues are “persons who have been selected to work together”. Presumably the enterprise requires working together rather than working alone. If our enterprise as faculty members is the education of students in some coherent systemic way, then we do need to work together. I’m not sure that’s what students experience, especially when course registration rolls around. Gymnastics are sometimes required to get things to fit; and one culprit is departments not talking to each other when scheduling their courses.

Collegiality seems to connote the idea of friendliness in working together. I’m in what I would deem a very collegial department. Many of my colleagues are also my friends. I have good working relationships, but the friendship extends beyond the work-related sphere. I count myself very blessed, as I have friends at other institutions in different departments with seemingly nasty backbiting egotistical colleagues. I don’t personally know these non-collegial faculty members so I can only imagine what it must be like to have to work with them; although I suspect that I wouldn’t encounter bad behavior should I happen to meet such a person. Often it takes some degree of familiarity to breed contempt.

I’d like to think that collegiality helps a department (or even college) thrive; perhaps it is necessary but not sufficient. Instead of administrators using it as an assessment, collegiality could and should be leveraged to fundamentally improve undergraduate education (the reason we’re there to work together). I’m skeptical with the way university administrations try to dictate policy to change culture. Maybe I’m naïve but it seems much more effective to build excellence through collegiality – it may take a little longer, seem a little more nebulous, but having experienced going through this process in my own department I can see the fruits of such an approach. I’m thankful to some of my older colleagues who worked hard at this, seemingly in the background, but with great results in less than a decade. Building a firm foundation (even if it’s unseen) means the house is unlikely to collapse even when buffeted by environmental changes and challenges.

I know some of my departmental colleagues very well; others not so well. Some I hang out with outside of work; others I don’t. Some I would call friends; others acquaintances – and certainly colleagues. But even if we aren’t personal friends, there seems to be a great deal of trust amongst my colleagues. Perhaps that’s one key element of the firm foundation: trust. There is a widening gap between different constituents of the university because of a lack of trust. Trust has to be built slowly but surely. It’s difficult to build or sustain with a rotating gallery of administrators or with top-down policy mandates. Building trust has taken a backseat to other initiatives and goals; things seemingly more visible that can be listed in a resume. I don’t know any shortcuts to building trust, but we need more of it. Mandating collegiality assessments indicates a sure lack of trust.

A Shift in Bonding

This past week, I’ve shifted my attention to thinking about chemical bonding, motivated by the benzene paper mentioned in my last blog post. It’s a nice break from my sabbatical research projects, especially since I get to think about teaching! I’ve been contemplating how to introduce some ideas from the benzene paper into my quantum chemistry course.

Looking at my most recent syllabi, I’ve typically spent 4-5 class periods (out of 42) on chemical bonding concepts not emphasized in the standard textbook I use for quantum chemistry (McQuarrie). I introduce the Heitler-London (HL) wavefunction for H₂ and discuss how it differs from the molecular orbital (MO) description. We delve into hybridization and the surprising case of bond angles in simple hydrides; sometimes we venture into so-called hypervalent bonding. There’s some Huckel theory and symmetry concepts related to the nodal theorem.

I’d like to approximately double this amount. What would I add? Largely concepts learned from Valence Bond (VB) theory beyond simple Lewis structures. I’ve already started with the HL wavefunction and some simple surprises. I’d like to show more connections between MO and VB approaches, emphasize the importance of Pauli repulsion, and further cement the notion of how different models are used to describe the ‘unseen’ behavior of electrons in chemical bonds. I’d also like to tackle the different types of bonds that are encountered. There are the strangely weak O–O and F–F bonds, the Rundle-Pimentel three-center-four-electron bonds, the one-electron metal bonds, and what goes on in high-strain structures.

To cover these, I’m thinking of centering these discussions around Charge-Shift Bonds (CSB). You’ve never heard of them? CSB proponents argue they are a unique class, and complement the two better-known classes: ionic and covalent bonds. I’ve known about CSB for a while, but with a literature search I came across and excellent recent review article (Angew. Chem. Int. Ed. 2020, 59, 984-1001) written by some of the stalwarts in the field. Is this new class of bonds warranted? The authors present arguments to answer two questions: “Do the bonds belonging to the new class have clearly different features than bonds that belong to formerly defined classes? Is the definition of the new class useful, and does it simulate chemists to make new predictions?” They conclude yes after providing some evidence, and I’m inclined to agree with them. What’s nice about their approach is that it brings in both MO and VB approaches, and takes Pauli repulsion very seriously. There’s also a nice connection to the virial ratio, which the students encounter when solving for the kinetic and potential energy of the hydrogen atom.

All this sounds nice, but if I’m going to add material, what should I cut? My course is already jam-packed with lots of good stuff. (The students might debate ‘good’; they certainly would agree with ‘jam-packed’.) Looking at my syllabus, I could cut the general derivation of the wave equation, reduce time spent on term symbols, cut out some of the math in the spherical harmonics derivation (Legendre polynomials) and in the Hartree-Fock wavefunction for H₂. That may or may not be 4-5 classes worth. I might be able to shave off other bits here and there, but then this brings up the question of whether to keep the textbook. The more I deviate from it, the more students don’t like it. That’s why I don’t use a textbook for second-semester P-Chem (statistical thermodynamics and kinetics). I’m seriously thinking of doing the same for quantum and writing up worksheets for every class. It will be a lot of work, but it might also be helpful should we have another coronavirus-like situation. (Another factor: the textbook has also increased significantly in price.)

I’m not slated to teach quantum next semester since I’m doing a special topics class on the chemical origins of life! Thus, I have time to think, plan, and work on an overhaul – I’m likely to teach quantum in Fall 2021. In the meantime, I’ve been enjoying thinking about teaching innovations. Last week I wrote out four examples of journal and glossary entries after pondering this as a key semester-long assignment for my special topics class. I’m also reminded, amidst a sabbatical mostly doing research, why I chose to be a professor at a liberal arts college rather than a research university – the love of teaching still excites me after so many years and I’ve been missing it this year!

Slater Chemical Bonding

“After 90 years, scientists reveal the structure of benzene.”

Since chemical bonding is one of my areas of expertise, I couldn’t resist the clickbait of this PhysOrg article. There’s a figure snapshot before the article begins. I can see what look like banana bonds. No surprises there. That’s old news, I thought. Quoting a scientist involved in the study, the media article says:

“What we found was very surprising,” said Professor Schmidt. “The electrons with what’s known as up-spin double-bonded, where those with down-spin single-bonded, and vice versa.”

Did you understand that sentence? I didn’t. It was downright confusing. Let’s look at the next quote.

“That isn’t how chemists think about benzene. Essentially it reduces the energy of the molecule, making it more stable, by getting electrons, which repel each other, out of each other’s way.”

Duh. Of course you’d want to reduce the overall energy of the molecule. Of course the electrons should repel and avoid each other. That is how chemists think about any molecule.

But the paper was published in Nature Communications (2020, 11, #1210). It has a very boring title: “The electronic structure of benzene from a tiling of the correlated 126-dimensional wavefunction.” Sounds esoteric? Well, benzene has N = 42 electrons, so 3N dimensions would be 126. Errr… okay.

I’m on sabbatical with all sorts of extra time on my hands. Maybe I’ll read this paper, even though it has nothing to do with any of my ongoing research projects.

Turns out to be quite interesting. (It’s open access so you can read it here.)

WARNING – Lots of unfiltered science-y jargon ahead!

I really liked that the authors set the stage by accounting for Slater determinants to maintain an anti-symmetrized wavefunction a la Pauli. When teaching quantum chemistry, I make a big deal about this. I also make a big deal about how chemists’ view of orbitals is hydrogen-like, even when multi-electron molecules have orbitals that likely look nothing like hydrogen atom orbitals. That’s lots of like. I try to emphasize how everything we’re doing in the second half of the semester is about approximations; we talk about how orbitals might be constructed differently, and the pros and cons of a one-electron Hartree-Fock (HF) approach.

The stability of a molecule is related to the strength of its chemical bonds. The heart of chemistry is making and breaking chemical bonds. For me, a chemist, quantum chemistry is at the heart of chemical bonding. So, as elusive and complex as they might be, it’s incumbent to learn about the two major approaches to chemical bonding (Molecular Orbital Theory and Valence Bond Theory). MO Theory often shows up in P-Chem textbooks. But a more advanced VB Theory does not. I make it a point to cover both models, because they have their strengths and weaknesses. My version of VB begins with the Heitler-London wavefunction, and then proceeds to add on additional configurations, mixing, and the like. We look at hybridization closely. I make a big deal about how and why chemists use different models in different situations.

Back to the benzene paper. I wasn’t familiar with the dynamic Voronoi Metropolis sampling, but it’s interesting that a much older Boys localization gives similar qualitative results. The banana bonds make a comeback in benzene. (When I first bring these up in P-Chem, students are aghast, and then are surprised how well they work.) But what’s novel is that when you separate the alpha and beta sets of electrons, they alternate, sorta Kekule-like but not exactly. They implicitly arrange themselves the way you’d expect if electron correlation was accounted for – and here’s the important part – both Pauli repulsion and standard electrostatic repulsion are considered. When we discuss Helium wavefunctions in class, I bring up the separation of spin-orbitals and its advantages. But I’ve shied away from talking about unrestricted HF or multi-configurational methods, beyond briefly saying something about configurational interaction to go pass the HF limit variationally.

Immediately after finishing the benzene paper, I did a quick search and downloaded the other four papers where the authors used the same approach. The most useful was the first paper (Phys. Chem. Chem. Phys. 2016, 18, 13385-13394). It explains their methodology more clearly, and very importantly they tackle the diatomics C₂, N₂, O₂, and F₂. We cover homonuclear diatomics in class with both MO and VB theory. And while advanced VB theory alludes to good old Lewis structures (and their limitations), the pairing restrictions ignore correlation. There’s an intuition involved in drawing good Lewis structures, or coming up with VB diagrams or MO diagrams. But I’ve often had a nagging feeling that something significant was missing. The authors position their starting point of Slater determinants as not being beholden to a particular theoretical view, and interestingly their results find resonance with Linnett’s double quartet theory; using tetrahedra rather than cubes (Lewis) as a fundamental building block makes more sense to me.

The water paper is the shortest and easiest to read (J. Phys. Chem. Lett. 2020, 11, 735-739). There’s a nice diagram that shows the difference between starting with a Hartree product for the particle-in-a-box versus a Slater determinant. I think I will use this the next time I teach quantum. I also liked the fact that their isosurfaces show that the water lone pairs aren’t so much rabbit ears but koala ears! My students will get a kick out of that. However, one counterintuitive thing that I haven’t yet wrapped my head around is why the tiling approach shows that the maximum electron density of the O–H bond lies so much closer to the less electronegative H. I understand that the lone pair density would be closer to the oxygen and the bond pair would be further away, and that the short bond means that Pauli repulsion will push the density away from the center. It’s just that electrostatic calculations seem to suggest the opposite. Without more molecules (NH₃, CH₄, H₂S, H₂Se), it’s hard to draw a conclusion.

In the water paper, the authors also try to partially reconcile the “disagreement” between MO and VB theory by delving into how one interprets the photoelectron spectrum of water. They do this by calculating the ground and excited states of the water cation. It’s a reasonable argument, but I’m not a spectroscopist so it’s hard to pronounce judgment either way. The other two papers discuss thinking about vibrations (more spectroscopy) and curly arrows. Information is a little scant in both papers, so I’m reserving judgment on those. But overall, I think this is the most exciting thing to come out of chemical bonding in recent years. Slater finally gets his due. And we now have a model that goes some way into distinguishing Pauli versus electrostatic repulsion. I will be modifying my quantum class appropriately.

P.S. This post has no pictures even though I know it would help. I didn’t want to post screenshots from the papers (copyright and all), and I was too lazy to make nice computer drawings of how I would depict these spin-orbitals. I’ll get to it when I have to do class prep.

Journal and Glossary

This Fall semester I will be teaching a special topics course on the “Chemical Origins of Life”. We will be reading the primary literature, starting with Stanley Miller’s famous 1953 paper, progressing through some of the significant milestones, grappling with recent findings, and speculating on the future of the field – maybe discussing finding life on Mars!

Here’s the overall plan: Early in the semester, for at least the first month, I will provide guiding questions for each paper, and lead the discussions. Midway through the semester, students will take over preparing the guiding questions and leading the discussions – how and when exactly that happens will depend on enrollment. In the later stages, I will take over leading again as students prepare for their final project: writing a paper and an oral presentation on recent work in the field. I will likely provide students with a list of potential topics; they would also be free to propose their own topics. There might be some short quizzes and possibly one short exam in the first half of the semester to solidify content knowledge, hopefully aiding students as they approach the final project.

I’m considering having the students keep a journal on their thoughts related to class, drawing from their readings and discussions. I’ve had students maintain blogs and participate in online discussion groups a couple of times in my smaller G-Chem classes, but with mixed results. I’m trying to navigate the balance between individual learning and communal learning. I emphasize the former over the latter, because each student as an individual must demonstrate understanding of chemistry – and this involves the hard work one must do individually grappling with the material, while getting help when you’re stuck! But I also recognize the latter can be important, and I encourage students in G-Chem and P-Chem to work together on problem sets and studying for exams.

Thus, I’m considering having the students submit their journals maybe every 3-4 weeks (with minimum two entries per week since class meets twice a week). Assuming these are electronic, I could assign one or two other peer readers, and the next submission should also contain an entry reflecting on reading a peer’s entries. As the instructor, I’m looking forward to reading these entries because it might give me a better idea what the students are thinking outside of class when they’re reading. I should probably provide some journal entry examples from my own reading, which means I actually need to start journaling. I also think a glossary should be included since I regularly need to look up the definition of a word when reading outside my field. My students will have a similar experience encountering new terminology in the papers they read.

I’m also thinking of having the students propose their own grade at the end of the semester. If they’ve been journaling, hopefully they’re more aware of how much they know, how much they don’t know, and how much they think they’re learning. They’d also know how much effort they’ve put into the class relative to their other classes. I’d like to know too, and I suspect it will be mentioned as justification for the proposed grade. I would still finally decide on the final grade. When I introduced exam self-grading in G-Chem last year, I noticed that some students would grade themselves higher or lower than what I would have given. (Their proposed grades had no impact on their actual grades.)

Maybe their last journal entry should be a self-evaluation of their learning upon re-reading their journal, and with that their proposed self-grade on whatever criteria they deem important. If the final project constitutes 30% of the grade, their discussion leading/prep 20%, other small assignments 20%, then the journal (and the nebulous “class participation”) might constitute 30%. Or maybe I shouldn’t think about percentage breakdowns and do a holistic evaluation at semester’s end. I don’t know. I’d like to de-emphasize grade-bean-counting. And I still have time to figure it out. What I should do is start writing a few journal entries with accompanying glossary!

Emergency Remote Teaching

Watching the spread of Covid-19 and its potential disruption to schools and universities is giving me pause. I’m not personally affected by precautionary regulations since I’m on sabbatical and not teaching. However, large classes at the institution I’m visiting have moved to online delivery; smaller classes are still meeting face-to-face. I’m sitting in on a small biochemistry class, where attendance is now taken in case contact tracing is required. The university has also been offering a slew of Zoom courses for faculty members.

What’s giving me pause is whether I would be prepared to switch to remote teaching if there was a health crisis or some other emergency, potentially lasting for weeks or months. I have on rare occasion missed a class or two. If so, it’s usually because I’m attending a conference, although feeling sufficiently unwell would also do it. I try not to travel when classes are in session because I don’t like missing class, and for the most part my body subconsciously waits for the break to break down and fall ill.

My department has an emergency backup teaching plan for our high enrollment multiple-section courses such as general chemistry. I’ve subbed for my colleagues when they were out sick or traveling, and they’ve done the same for me. Some folks opt to cover their own classes with some online approach with video and discussion. But all these are typically one-off occasions – my colleagues and I prefer (I think) to be with our classes in person; that’s why we’re teaching at a liberal arts college. I’m a proponent of live relational learning, and chemistry is a challenging subject to learn even in the best of circumstances.

I maintain my course websites which contain detailed information and some materials for delivery, although I’ve never done a video-lecture. One of my courses (P-Chem 2) has detailed fill-in-the-blanks handouts for every class session because I do not use a textbook. It should be fairly straightforward for me to do video-capture for that class, or any of my classes, although I would need to learn and practice. I’d be more inclined to write out my lecture notes in full and add annotations before sending them to my students – I think this would be more effective but I don’t know for sure. One year (in the old days), I gave out photocopies of my P-Chem notes to students before class, in the hope that not having to maniacally write in class, they could concentrate on my explanations. I’m not sure there was much effect, except some students skipped class more often.

If, as I believe, a core aspect of teaching is my relationship with students, then I expect that in a Covid-like crisis, I would still regularly meet and discuss things with my students over Zoom, Facebook or other platforms. I think my students and I would both appreciate live Q&A, rather than asynchronous back-and-forth e-mails. Chemical structures, equations with symbols/sub/superscripts, and visual schemes, would likely communicate better through video – along with accompanying audio explanations. It’s no fun being isolated or quarantined, so I’m thankful for today’s technology that allows for (virtual) interpersonal communication.

For institutions as a whole, being affected by Covid-19 brings greater challenges. On top of instructional issues, residential colleges with students living on campus present even greater challenges – from additional cleaning to changes in dining services. On the university administration front, splitting your teams so that half the group is telecommuting at any one time is a standard operating procedure to minimize risk in these circumstances. Here’s a link to the CDC interim guidance to higher education institutes on Covid-19. On top of that, having to combat fake news, panic, xenophobic attitudes; all of this presents quite the challenge. My worries about online emergency teaching are a small drop in the bucket; but it’s better to think ahead and be prepared. I’ve been forewarned.

Multimodal Learning in Chemistry

Ask the Cognitive Scientist is a column in the quarterly newsletter American Educator, written by Daniel Willingham. In my quest to understanding the role of cognition in learning, I’ve read a number of Willingham’s more technical papers. But to communicate these ideas, I’ve found his columns helpful. I’d been thinking about why the idea of ‘learning styles’ persists amongst my students despite the evidence, i.e., students think they have a preferred modality of learning and that if only they were taught through that modality they would do better in their classes. Sure enough, Willingham addresses this in the summer 2005 issue.

He begins his column by emphasizing his main point: “What cognitive science has taught us is that children do differ in their abilities with different modalities, but teaching the child in his best modality doesn’t affect his educational achievement. What does matter is whether the child is taught in the content’s best modality. All students learn more when content drives the choice of modality. In this column, I will describe some of the research on matching modality strength to the modality of instruction. I will also address why the idea of tailoring instruction to a student’s best modality is so enduring – despite substantial evidence that it is wrong.”

At this point, you should just read his column. I won’t go over his arguments (which I find persuasive) but instead consider what this means for teaching chemistry.

Let’s dive in. What content modalities do we use in chemistry?

I can’t imagine learning chemistry without pictures. We’re trying to imagine tiny ‘invisible’ particles called molecules. These molecules consist of smaller particles called atoms which are held together by chemical bonds. If you’re reading this, you’re reading a bunch of words. And if these words sound like gobbledygook to you… It would be much easier to show you a picture of what to imagine – here’s the ubiquitous water molecule made up of one oxygen atom (red) and two hydrogen atoms (white). But different representations can emphasize different aspects, but can also be misleading in other aspects.

Chemistry takes place when molecules collide, breaking some chemical bonds, and re-forming new chemical bonds. Atoms from one molecule might move to another as part of this process. This can be viewed in video; the dynamic picture conveys this much better than a static picture. But this is a very idealized view because most chemistry that we ‘experience’ takes place in solution where gazillions of molecules with gazillions of others. The video would look like a mess and the viewer would be hard-pressed to focus on what’s important.

Thus, abstraction is a key skill that the chemistry student must learn. There are many different kinds of models (none are anywhere close to perfect) used for all manner of chemistry we’re trying to illustrate or explain. Using graphs with a time axis allows us to abstract a dynamic situation using a seemingly static representation. Mathematical equations help to encapsulate what’s going on even if they can be hard to understand when first introduced. And I suspect it helps the students when I put together a seemingly multi-modal presentation while speaking, gesturing and writing. I can understand why it’s difficult to just ‘read the textbook’ even with electronic versions that includes fancy graphics, hyperlinks, and videos.

I’ve been having a similar experience this semester while sitting in on a colleague’s survey of biochemistry course. I’ve looked into a standard fat biochem textbook as a reference when I’ve needed some information. I’ve also read the Manga version, but I confess that I’ve forgotten much of it. Being in class ‘live’ is helping me learn the material in a much more facile way, or at least that’s how it feels. Admittedly, I haven’t been doing the reading or any of the coursework; although I do have strong chemistry scaffolding and some biological knowledge. To really learn the material, I’d likely have to teach biochemistry, and I might do so someday!

Another important aspect of many chemistry classes is learning lab skills. One might call this the ‘kinesthetic’ modality, although I think that basic observation and manipulation skills are a key aspect to one’s chemical education. Measuring out the chemicals and making solutions bridges the abstract to reality. Learning how to use an instrument to take data reinforces the ‘mediated’ nature of chemistry – using a device to help us ‘see’ what we cannot see with the naked eye. Students manipulate 3D molecular models to get a sense of molecular shape (important in how molecules interact with one another) that would otherwise be difficult to represent in an image.

I’d like to think that after all this, the students do learn some chemistry. Some learn much, others learn little, at least based on the spread in final exam scores. I still meet people who upon learning that I teach chemistry say that they were ‘bad’ at chemistry and didn’t understand it. Very few blame their teachers. One thing that Willingham argues in another Ask the Cognitive Scientist column is that student need to be thinking about the subject matter to remember it. That thinking (which is hard work) could happen while listening to a lecture or doing a hands-on experiment in lab. Equally, there could be very little thought in either activity. There are so many factors; I suppose that’s why I continue to be fascinated by teaching and learning.