Monday, December 29, 2014

"Gatekeeping" in Intro Chem Lab

Over at Chemjobber, there's an interesting discussion around "gatekeeping" - intentionally using introductory science courses as weed-outs to restrict access to higher-level material - and whether anyone actually does this in practice. Although I don't think of my experience in these terms, I'll relate my recollections and let readers judge for themselves.

Stone walkway, 2014
At Big State University, I was part of a teaching assistant (TA) team tackling Chemistry 101 lab. These were classic experiments: density, dilutions, diffracting light, quantitative analysis, titrations, measuring exotherms. TAs not only ran labs, but lectured beforehand, graded reports, filled out student evaluations, and tallied final grades. 

While the content wasn't enough to weed out dedicated students, the lab policies certainly may have been. The implied ideology went: "if you can't follow these rules now, you'll never cut the higher-level labs.

Pass in a report 1 minute past the start of lecture? Zero
Handwritten report? Zero.
Blatant disregard for lab equipment? Zero.
Show up to lab without proper PPE? Go home
If a student had not replaced broken glassware by semester's end? Fail.
Evidence of plagiarism from the lab manual or suspected from others' reports? Fail
Miss the final exam? (Yes, a final lab exam...) Fail.

Though the TAs tried valiantly to corral teach the ~400 students who came through our section each semester, my honest memory was that we usually kept fewer than 250 by term's end.


  1. Cruelty which was unknown to me before...

  2. Am I the only one who thinks all of these sound pretty fair?

    Diffracting coloured light? I'm interested to figure out what the point of that lab is?

    1. D'oh! You win - I've changed the post accordingly. The point of the lab was to decompose various light sources (flames, fluorescent bulbs, etc) into their respective wavelengths, a sort of mock-spectroscopy.

  3. My opinion concerning these rules depends in part on whether the students are primarily full-time students living on or near campus, or whether there are significant numbers of part-time and commuter students.

    At first glance, it sounds kind of draconian. If the only purpose of the class is to teach people about chemistry labs, and grade based on what they can demonstrate that they learned, then these rules seem superfluous to the purpose. If, however, part of the purpose of a freshman class is, as part of the wider college experience, to impart certain habits and discipline, then it seems like a necessary corrective to all of the temptations faced by freshmen living away from home for the first time, unsupervised, with ready access to alcohol. It's easy to say "Oh, they should get a chance....", but then you think about the logistics of hundreds of students and what it takes to deal with all of their excuses. Think about the task of making exceptions yet remaining "fair" and "consistent", and what happens when a student with (circle all that apply: pushy parents, good lawyers, a litigious nature) is not given the same break as some other kid.

    At some point you have to say "OK, you're adults, you have the privilege of being in college, take some responsibility and get your sh!t together." If you beat this into them as freshmen, you can ease up a bit in subsequent years. But if you get them used to excuses and exceptions and second, third, and fourth chances, you get seniors who still don't have their sh!t together.

    All that said, I would be a bit gentler at a commuter school, because the students face far more constraints that they have no control over. But still, you have to start them on good habits as freshmen.

    1. I should add that when a TA is tasked with rule enforcement, that TA is often close in age to the students. That already undercuts some of their authority. Female TAs often face additional challenges to their authority with students. And regardless of gender or other circumstances, they are inexperienced. Asking inexperienced people, with tenuous authority, to arbitrate exceptions to rules, is a recipe for disaster. Strict rules stiffen the spines of TAs and make it harder for undergrads to walk all over them.

      I'm a tenured professor. I can maintain authority while being somewhat flexible. A 22 year-old student can't do so nearly as easily.

    2. An excellent point. Exceptions are difficult when you're first faced with lecturing to the multitudes, who aren't that much younger than their TAs. Thanks for the input.

    3. Even for a class primarily for commuters, I would still say it's pretty important that things start on time. Most lab classes have students doing things they've never done before that are potentially dangerous. If they feel rushed they are more likely to make mistakes (even if you've done it a thousand times before you're more likely to make a mistake if you're rushed). I'd be more likely to cut some slack to someone if there was a bad accident on the turnpike, or whatever, but it shouldn't be a habit. If someone is commuting and there is a potential for traffic issues, they need to work their schedule so they err on the side of showing up early.

  4. I believe Thoreau hits the nail on the head. I had the privilege of earning my doctorate from UC Davis, and thus had the... erm... privilege of TAing there as well. I am originally not from California, and the diversity of backgrounds you see there was truly amazing to me. A large portion of the students are commuters; many of the students attended a JuCo beforehand; and an even larger portion of the students (in the first year chem classes) are in their first few months of being in the US. On top of that, UC Davis is attended by many high-achieving students who are in the exact same entry-level class as those mentioned previously. (There is a honors chem class, but it is so small in comparison to the total number of students enrolled in entry level chemistry that you almost forget it exists) There are typically around 3500 students at any one time taking entry level chemistry at UCD, so making exceptions for a few students isn't really a luxury that we were afforded. We had draconian rules because it was simply the only way to maintain order with that many students.

  5. When I taught organic lab at a large university we didn't have these very strict policies, but maybe we should have. I think they make a lot of sense from a logistics and safety point of view.

    Letting people show up late to a lab class could cause problems: At the beginning of each lab, I would have a mini-lecture reviewing the most important points of the experiment, and I'd demonstrate any particular apparatus (how to set up distillation, use the rotovap, etc.), as well emphasize aspects related to safety. Then there was a brief quiz just to reiterate this and make sure they were paying attention (not at all challenging if they had prepared for the lab beforehand as they were instructed to do). Even when there were no issues and everything started on time, there were always a few students who couldn't finish within the allotted schedule. There was some buffer time between lab sections, but we really couldn't have students going very far over because someone else would need to be using their hood next. If someone showed up late and missed the introductory lecture, I had to talk to them to make sure they had prepared and that they understood how to carry out the experiment, which took my time away from paying attention to the other students.

    You don't want someone who is unprepared and rushing through an experiment, because that's when accidents are most likely to happen, and they could be dangerous to themselves and others. So I feel like these rules are perfectly fine: They emphasize that the students must take the lab seriously

  6. Hah, where I TA the sophomore organic lab is just participation: show up to *most* lab sessions (of course it's acceptable to just show up whenever you want if you "can't" make your scheduled time!), hand in a piece of paper that you label (but is usually not even close to an acceptable) "report" and congratulations! you get 100% in "orgo" lab!!! Students are technically required to prepare for their sessions but, seeing as the coordinator is super chummy with the undergrads, what little authority TAs had to enforce any kind of standards gets yanked out from under them. Less than half of the students actually get any product from the experiments (don't worry, they still get A's) and then we wonder why they are completely helpless for their junior/senior projects...

  7. I have a feeling that a lot of those students who are "weeded out" would not have passed even in a more supportive environment. In my own experience as a TA for o-chem lab, I would offer to help my students with their lab reports. My standing offer was that if any student turned in their report two days before the deadline (most reports were due in one to two weeks), I would work with them and guarantee an A. I only ever had one student take up the offer, and she was already coasting on a 95%.

  8. z makes a good point—it's partly a safety and consistency issue. Our policies at [Southern Engineering Mecca] are not quite as draconian as you describe (we rent out PPE to students who need it, for example), but introducing flexibility also causes ambiguities to arise...better to be a little tougher and remain consistent than get lax and potentially introduce hazards or unfairness.