Tag Archives: physics education research

Urination and Physics

The Times Education Supplement [TES] is known as a fairly conservative British publication, focusing on policy news, endorsements of the teaching profession, and op-eds by teachers. So it was surprising to see a click-bait headline relating to physics education research: “Taking the pee out of physics: How boys are getting a leg-up“. Unlike many submitted posts, this one is not identified as being written by a blogger, and comments are disabled — we are intended to treat this as real research news.

The crux of the argument is this: we have a gender gap in physics scores on standardized assessments. That gap seems to be most pronounced on tasks involving 2-dimensional motion. One explanation for the discrepancy is that boys have more experience with balls, rockets, cannons, and so forth because of the social conditioning they experience as children. However, the authors note that female students in the “ultra-masculine environment” of a military school show the same gender gap. Thus, they conclude that ball sports and play-acting war isn’t the factor. Instead, they propose that boys playfully urinate, and thus have experience with projectile motion in a way that girls don’t.

There is a lot about the article that is objectionable.

1. This article isn’t based on published scientific work, it doesn’t refer to a submitted manuscript, and the authors don’t have any related publications in the literature. This isn’t an idea that has been vetted by peer review. More importantly, it isn’t a mature scientific idea: the authors have proposed a hypothesis, but haven’t actually carried out the experiment.

It would be easy to test: survey men about their childhood urination habits, and about their proficiency with physics. Maybe throw a tricky physics problem at them, too. But the authors didn’t do this, preferring to write about the idea as if it were too obvious to need verification. This sort of speculative science is problematic, and popularizing ideas that haven’t been vetted empirically has been problematic in physics in recent years. It is particularly bad in the field of physics education research, which is struggling to be recognized as proper science by a dubious physics community.

2. Since the authors didn’t conduct a study, I did. I asked 25 people (THANK YOU!!) to answer four questions: were they sports fans as children, did they playfully urinate as children, and were they good at physics in school? I also asked them which angle would optimize the range of a projectile in the real-world case where air friction cannot be neglected — someone familiar with projectile motion either experimentally or theoretically should know that slightly decreasing the angle from 45 degrees (the theoretical optimum) will increase the range when air friction is considered.

The results of the survey show that neither urination nor sports were strong predictors for physics ability. The strongest relationship was between sports and success on the physics problem, but this did not reach an adequate level of confidence*. In short, had the authors actually tested their hypothesis, they would have found it incorrect.

3. The language used in the article makes it clear that this is click-bait rather than a serious attempt to introduce a new idea. Consider the following lines: “those sparkling arcs of urine”, “pee-based-game-playing”, and “…despite the surface layer of toilet humour, and the implication that physics may be little more than a pissing contest, we’re making a serious point.”

Unfortunately, with phrasing like that, the authors are not.

4. Another point is made by Brett Hall: projectile motion isn’t a topic that occurs at the start of the curriculum, yet the gender gap is apparent from early in the physics course. Likewise, the authors suggest focusing on energy conservation first, rather than projectile motion, but this is something that is already done in many classrooms.

5. Research by Zahra Hazari and others points to socio-cultural factors (identity,  home and school support) being the most relevant to explain why girls opt out of physics. I wouldn’t argue that the gender gap is an understood problem, but the authors present it as wholly-unsolved (perhaps to increase the audience’s willingness to accept their unorthodox idea) when it isn’t.

6. [addition 18 September] On further reflection, it is more clear to me that the phrasing and positioning of this idea to be damaging and troublesome, in addition to being incorrect and click-bait. A phrase like “why don’t young women perform as well in physics?” presupposes that the cause is a deficiency in the women, rather than the sexist culture in which they are raised and on whose assessments they are being found wanting. I hope no teenage girl hears of this incorrect hypothesis, reads this article, or absorbs the various ripples it is making in the news media.

Lastly, a note about ad hominem rebuttals. I think that most men would look at this idea and disagree because of their personal experience. I’ve seen some rejection of this hypothesis because the primary and secondary authors are female. However, there is value in the perspective of an outsider: we do a lot of things unconsciously, and only an external viewer would be able to make connections we might otherwise miss. Dismissing this work about male urination because the authors are female is incorrect.

I think that’s about all I want to say about this idea. Hopefully we can forget it now.

* The n=24 study I did was enough to show that the urination=physics ability hypothesis cannot be the primary explanation for the gender gap. However, it is possible that there is still a small correlation. As pointed out by Steve Zagieboylo, however, this pathway likely goes boy-sports-physics rather than boy-urination-physics, given the strong social differentiation that boys face. The results from my study suggest this but, since the effect is smaller, I cannot claim to have discovered anything with the small sample I used.

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Scientific Reasoning in Physics

For many students, high school or university science courses are their last formal contact with the lofty ideals and approaches of organized science. Educators have traditionally done a poor job equipping such students with the vaunted skills of scientific reasoning. In this post, I’ll explore why, and look at how we might improve our teaching.

The 1977 paper of Fuller, Karplus & Lawson [FKL] was the first in the modern era to combine the concerns of developmental psychology and tertiary-level physics education. FKL identifies three ways “patterns of reasoning” that are more prevalent among physicists:

    1. identifying and focusing on the most important variables
    2. using propositional logic
    3. using proportions

These are not unique to physics: my mother could see a broken window and know to look for the baseball, spot holes in my alibis and, deduce that cooking six-sevenths of a baked omelet that normally requires a dozen eggs means you scale it back to about ten. However, FKL argue, their consistent use is a hallmark of both scientific reasoning and progression to Piaget’s formal operational stage of development. The argument further suggests that physicist-style reasoning is uncommon because formal operation is uncommon (FKL suggest a third of American adults do not employ formal operation patterns), poorly promoted in the public sphere, and more cognitively difficult than concrete operation. Consider the comparison below (from FKL): where do high school students fit?

Screen Shot 2013-08-24 at 2.39.43 PM

Stephens & Clement (2010) identifies three patterns of thought associated with the analysis of models in physics. They note that, in group settings, students might either generate or run with  (ie: follow on from another student) the approach. Their patterns of thought are:

  1. Using analogies
  2. Considering extreme cases
  3. Thought experiments (gedankenexperiment)

In the American Next Generation Science Standards [NGSS], scientific skills and practices — essentially an expanded vision of Fuller’s view of scientific reasoning — comprises the first of three dimensions, along with “cross-cutting concepts” and the actual content. The “practices” are such statements as:

Apply scientific reasoning to show why the data or evidence is adequate for the explanation or conclusion (for gr. 6-8, p. 27)

Clearly, scientific reasoning is important. But it’s also difficult to teach. Steinberg, Cormier & Fernandez (2009) [SCF] taught a summer enrichment course in astrophysics for New York high school students. Their approach — presenting physical models, providing no direct answers, etc — provided only modest returns. Book-end tasks asking students to motivate heliocentrism (or geocentrism) saw a dramatic increase in the number of geocentrists (42%in the exit task!) with only anecdotal improvements in reasoning. A second end-task saw that 95% chose “I don’t know” about the existence of black holes, indicating that this inquiry-heavy approach might have swung the pendulum so far as to push most students to adopt a highly positivistic view of science.

At the undergraduate level, Moore & Rubbo (2012) note that non-STEM majors performed worse on Lawson’s Classroom Test of Formal Reasoning [LCTFR (also LCTSR)] than STEM students (54% vs 75%). Worse, although the non-STEM students made significant gains on content-based tests (38% to 41%), the post-course gains on the LCTFR were marginal (6%). In a class with explicit instruction on scientific reasoning, LCTFR gains were more substantial (68%). Small sample sizes, particularly for the last (N=14), means that this conclusion should be considered only a suggestion.

Otero & Gray (2007) note a much smaller effect: in a larger study (N=189) of the PET/PSET curriculum, the students achieved an 8.8% increase on the CLASS assessment.

In addition to the LCTFR (Arizona) and the CLASS (Colorado), there are at least three other recent tools for analyzing student understandings of scientific processes. The MPEX was developed by a team from Maryland and adopted by SCF, above. EBAPS, from Berkeley, has questions that apply to students who do not have experience as physics students. VASS (Arizona) aims to determine views about physics, rather than focusing on reasoning skills.

Another approach to determining students’ thinking is to observe gestures. Stephens & Clement (2007) have been working on this. Among my ESOL students, I’ve seen abundant use of gestures, not only shape-, movement-, and force-indicating, but also gestures to represent the universe and direct representations of abstract concepts such as magnetic fields.