The following is a letter in response to the article “What Should College Students Learn?” by Jay Pasachoff, which appeared in the News and Commentary section in AER Issue 1.
I read with interest Jay Pasachoff's piece in the first issue of the Astronomy Education Review. My wife brought the contentious articles in The Physics Teacher to my attention several months ago, and I have given the issue a great deal of thought.
In my view (which is much closer to Pasachoff's than that of the “educational establishment”), the argument on what to teach ends up depending critically on two assumptions made by the establishment. The first point is the establishment's tacit assumption that moon phases and seasons (“classical” astronomy) are so much more important than galaxies and stars (“modern” astronomy) that they should be given overriding authority. That is, the establishment believes that if students need an entire semester to understand those topics, then a whole semester will be used, since these are the most critical ideas. The second tacit assumption is that without a complete understanding of classical astronomy, and without developing the reasoning tools necessary for such an understanding, students are unable to comprehend modern astronomy.
It appears to me that both of those assumptions are false. While students have much greater exposure to classical astronomy than modern astronomy in their daily lives (do galaxies actually matter to anybody except astronomers?), this does not, by itself, require that students have complete knowledge of classical astronomy topics. This is trivially shown by the fact that most people get along quite well in their lives without much understanding of classical astronomy.
The second assumption is also incorrect, as one piece of knowledge is not necessarily predicated on another. For example, it would be senseless and dangerous to avoid discussing the significance of traffic lights with a beginning driver, until such time as the driver can explain the details of a fuel-injection system. A personal anecdote proves this in a technical area. I did well in first-quarter chemistry in college, but less well in second-quarter chemistry. Yet even though I had great difficulty computing the pH of the product of the combination of two individual solutions in a test tube, I still have an elementary understanding of the nature of DNA.
Not only is comprehending stellar nucleosynthesis independent of being able to estimate the altitude of Polaris above your horizon, but it seems to me that to a large extent, understanding classical astronomy requires a different skill set and reasoning abilities than understanding modern astronomy. Classical astronomy, as I defined it above, is primarily qualitative and geometric in nature—that is, what is actually required for an understanding of most topics in classical astronomy is the ability to visualize two (or more) rotating spheres in a three-dimensional space. I have found that this kind of geometric visualization is among the most difficult things for my students to master. While necessary for an understanding of classical astronomy, that skill has little relevance to understanding stars. In fact, my students have a much easier time with stellar properties (for example, understanding why a red supergiant must be more luminous than a white dwarf, even though the white dwarf has a much hotter surface) than with classical topics.
My own view is that in a single-semester survey course, such as the one I have taught twenty times here at Penn, the seasons and lunar phases should be taught, but they must be taught as just two ideas among many. If some students do not “get” them, then unfortunately, that is the way it is. But those same students might still be able to comprehend the idea of black holes having escape velocities of c at the Schwarzschild radius.
Jeff Goldader can be reached at email@example.com.
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