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Pitfalls of Metaphors: Does Warm Air Hold More Water?

Preface

The following is a guest post by Glenn Dolphin (aka "Flipper"), of the University of Calgary Department of Geosciences.

This discussion first appeared in the ESPRIT list server, a lively forum for discussion of earth science teaching, mostly at the secondary school level. When Flipper's ideas below came forth, there had been an extensive multi-person, multi-day discussion of whether it was useful or misleading to tell students, during their study of weather and climate, that "warm air holds more water vapor than cold air." Although this and synonymous statements are common in popular science treatments (for example, here), this form of explanation has been roundly criticized in other expositions for the public (for example, here and here).

A point of view held by several teachers could be summarized by one who wrote: "As I see it, declaring that air 'holds' water isn't nearly as awful as it's made out to be." I was reminded of my blog post and followup comments about Telling Lies to Children, asking where is the borderline between a pedagogically valuable simplification and a lie. Air "holding" water is not literally true; it is a metaphor in which air is compared to a container with a limited holding capacity. Metaphors can be valuable tools for helping the human mind come to grips with (another metaphor) an unfamiliar concept. But they also have pitfalls, as explored in the guest post below.

-----Kim Kastens--Earth & Mind co-editor

Guest blog post

In my research, I am looking at the metaphors we (experts, for the most part) use in science and their effect on how students (novices) understand them. We use many metaphors (selfish gene, black hole, big bang, electron cloud, tectonic plate). As experts, we may very well be able to use "hold" if we have a good physical understanding for the air/water system. However, people who don't, like our novice students, will generate meaning based on their own physical experiences of containers that hold things. This could then lead to difficulties in understanding, most likely because they will always start from this point, and not give other meanings a chance. More

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What precursor understandings underlie the ability to make meaning from data?

I've been thinking a lot recently about how scientists and students make meaning from data, spurred in part by the Earth Cube education end-users workshop. Among other things, I've been trying to understand what kinds of deeply foundational understandings might be constructed by young children through unstructured observation using the human senses, and then later re-purposed as they begin to work with data.

Here is one candidate: Future data users need to understand that:

• events in the world leave traces, and
• by looking the traces, we can make inferences about the events.
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Is the Fourth Paradigm Really New?

I have a long-standing interest in the use of data in education, so I've been reading with interest several articles and a book concerned with the so-called "Fourth Paradigm" of science, in which insights are wrested from vast troves of existing data. The Fourth Paradigm is envisioned as a new method of pushing forward the frontiers of knowledge, enabled by new technologies for gathering, manipulating, analyzing and displaying data. The term seems to have originated with Jim Gray, a Technical Fellow and visionary at Microsoft's eScience group, who was lost at sea in 2007. The first three paradigms, in this view, would be empirical observation and experimentation, analytical or theoretical approaches, and computational science or simulation. Earth and Environmental Sciences are well represented in the book, with essays on data-rich ecological science, ocean science, and space science.

I am finding these readings very stimulating and worthwhile. But I question whether this way of making meaning from the complexity of nature is really so new. More

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Too Fast to Measure

I'm thrilled to report that the book that grew out of the Synthesis project, the parent project of this blog, is now out: Earth & Mind II: A Synthesis of Research on Thinking and Learning in the Geosciences, Geological Society of America Special Publication 486, edited by Cathy Manduca and myself. It's available from the Geological Society of America bookstore ( This site may be offline. )

However, having shared my thrill at holding the book in my hands, I have to admit that there are some ideas in the book that I have already outgrown during the months that the book has been in production. More

"Some Students Will..."

Recently my "Teaching & Learning Concepts In Earth Sciences" students and I renovated one of my old data-using lab activities, from the days when I used to teach "Planet Earth" to non-science majors. The old version of the activity led students step-by-step through a series of manipulations of an on-line global data base, using a professional data visualization tool. The old directions provided a lot of scaffolding for how to make data displays of ocean salinity in and around the Mediterranean Sea, but little support for how to extract insights about earth processes from those displays. The new version assumes that students are already pretty adept at getting computer apps to do what they want, and refocuses the scaffolding on how to think like a geoscientist, how to think about the meaning of the data. More