Monthly Archives: March 2014

Radiometric dating with cookies

Detail of the face of the astronomical clock in PragueThe media project for ILT was due yesterday, so naturally I’m posting it today instead.  I blame the delay on ambient noise makers of the four-legged variety.  (If I ever had a production company I would call it “Can we play now?” and the logo would be a tennis ball.)  My media project is a screencast about radiometric dating.  I used an analogy that has worked well for me in the past—eating cookies.  The cookie-eating analogy lets me explain the main idea behind radiometric dating in an intuitive way, and it also allows me to address a common misconception about the meaning of the term “half-life.”

This process is new to me, and I found it to be relatively painless, other than having to listen to my own voice over and over again.  I was happy to have iMovie to splice and dice QuickTime recordings to remove misspeaking, and to take out some of the more obvious pops, breaths, and thumps.  The biggest problem I experienced was underestimating the extent of image degradation upon sharing the video to YouTube.  Even with the highest quality setting, the text of my image credits is difficult to see.  Some of the images that I didn’t create myself are historical and have been in the public domain for a very long time.  However, three of the images aren’t historical, and they are important to credit.  To avoid re-recording the screencast in its entirety, I added image credits to the end.

The philosophy behind the design of my screencast is based on the idea that learning is a cumulative process.  If you don’t have a good foundation, you don’t really have anything.  My video is quite basic.  I avoided the radiometric decay equation, and the definition of the term “isotope.”  In an example, I used the elements uranium and lead because they are elements most people have heard of before (unlike samarium, neodymium, rubidium, or strontium).  Carbon-14 would otherwise be a natural choice because people tend to be familiar with carbon-14 dating, but it doesn’t work for the example, or for rocks in general.

There are many resources online to handle the more complex details of radiometric dating.  My goal was to establish the essential underlying ideas, and to convince students that radiometric dating is something they can understand.  If that is accomplished, the fear factor is reduced, and it is much easier to stuff information into brains.

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Open textbooks

The Sun: hotter than the bottom of the ocean (Credit: NASA/ European Space Agency)

The Sun: hotter than the bottom of the ocean (Credit: NASA/ European Space Agency)

A few weeks have gone by and I’m still thinking about textbooks. I’ve wondered before about the feasibility of creating an open textbook for introductory physical geology.  I got as far as sketching out some of the ideas and stopped when it became clear that a lot of work would be involved.

My most recent thinking about open textbooks was motivated by learning some startling facts from my students:  (1) At sea level, water boils at 1007°C.  (2) In areas on the ocean floor where new ocean crust is produced, water can be heated up to 10,007°C.

Setting aside for a moment the fact that that my students didn’t see anything wrong with water boiling at 1007°C, or with water on the ocean floor being a little shy of twice the sun’s surface temperature, what bothered me is that they encountered this information in their textbook.  I get that typos happen.  I’ve made some in my own course materials. The issue is that they are very hard to fix.  Ideally, I should be able to go into a document, change 1007°C to 100°C, and hit “update.”  Voila.  Problem solved.  Instead, I emailed the publisher’s salesperson for my region and told him about the error.  If he passes my email on to the right person, then in two years when the new edition comes out, water might once again boil at 100°C.

This is why writing my own textbook has a certain appeal.  Because no one is going to pay me to do it, I might as well make it freely available online.  It is free and relatively easy to make the textbook look pretty and to put it in places and formats that allow convenient student access.  The main difficulties are twofold:  First, I have to write it and find appropriate images that I am legally entitled to use.  Second, if done properly, I will have made use of online open education resources, and that means continually monitoring those resources to make sure they haven’t changed in unacceptable ways, or disappeared altogether.

When looking at a task requiring this much work, it is wise to see if someone else has already done the work for you, or is in the process of doing so.  Sadly, it appears no one has seen fit to build what I need.  It is also wise to see if others are interested in accomplishing the same task. Ideally, a project like this would involve a number of contributors with a wide range of expertise.  Perhaps a book sprint could be organized.  These are remarkable events during which a group of cloistered writers spends three to five days working on the book, facilitated by a company which organizes and feeds them.  At the end of five days a finished product is ready to upload… and apparently it is a good one.

Who knows—after years of writing fixes for course materials, I might have enough for a textbook anyway.

Categories: Learning technologies, Textbooks | Tags: , , , , , | 1 Comment

A little birdie told me, part 2

Archeopteryx fossil

Two posts ago I discussed the use of Twitter as a way to get students to apply what they learn in the classroom to geology-related news and science stories.  There is another educational angle to Twitter exemplified by @RealTimeWWII.  This feed maps events of the Second World War onto the present day.  @RealTimeWWII is currently tweeting about 1942.  This means that on 22 March 2014 the tweets will be about events that occurred on 22 March 1942.  @RealTimeWWII is a very effective way to bring the human experience of the past into the present.  Could this approach help to bring geological events to life?

The best events to tweet about would provide ample geological details in addition to historical ones.  For example, tweeting about a volcanic eruption would be better than tweeting about an earthquake: much of the geological action of an earthquake happens where no-one can observe it, and the activity that leads to the earthquake takes place over very long timescales and with few discrete events.  There is no human experience associated with stress building up in tectonic plates over timescales much greater than a human lifetime.  We can feel vibrations, but rarely can we watch tectonic plates slipping past each other.  In contrast, volcanic eruptions are heralded by readily observable geological events, eruptions evolve as they proceed, and terrain is modified on timescales humans can comprehend.

I think the perspective of an observer is key to making the tweets more than simply a timeline.  Consider the 1883 eruption of Krakatau—it would be possible to tweet an impersonal account of what the volcano was doing.  However, there are a surprising number of first-person narratives from Javanese and Dutch islanders who encountered tsunamis and pyroclastic flows first-hand, and from passengers on ships in the Sunda Strait who saw and felt the final earth-shattering (literally) explosion.  The Royal Society’s 1888 report, The Eruption of Krakatoa and Subsequent Phenomena contains pages of tables devoted to reports of what different witnesses heard when the final explosion happened.  Thanks to brand-new transoceanic telegraph cables, the events were also reported in newspapers around the world.

The human experience represents but a tiny sliver of geological time, and detailed accessible records of human experience cover only a sliver of that sliver.  This means having an observer could present some interesting creative and scientific challenges.  The task of reconstructing the eruption of Vesuvius in 79 CE from the letters of Pliny the Younger to Tacitus and the scientific literature would be more difficult that recreating the events of Krakatau, but not nearly as difficult as constructing a narrative for the mind-bending extremes of supervolcano Toba…which happened 74,000 years ago at a time when we shared the planet with Neanderthals and Homo floresiensis (the “Hobbit” people).  Now that would be an interesting enterprise.

The ultimate project would be to condense all 4.5 billion years of earth history into a single year of tweets…but who would be the observer for the first billion years before a sentient cyanobacterium could be recruited?

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Thank you very much John Wiley & Sons

Folded beds of Totoralillo Formation (Lower Cretaceous). Quebrada de Las Penas. Atacama Province, Chile. No date. (USGS)

Folded beds of Totoralillo Formation (Lower Cretaceous). Quebrada de Las Penas. Atacama Province, Chile. No date. (USGS)

This week’s post was supposed to be about using Twitter to teach geology, but work intervened.  One of the textbooks I use, Structural Geology of Rocks and Regions (Davis, Reynolds & Kluth), was updated as a third edition in 2012.  Unfortunately I didn’t become aware of this until two days ago when I received a copy in the mail and found that a course amendment document was urgently required for my structural geology course at Athabasca University.

This third edition was released for exactly the right reasons.  The authors have made substantial changes and, so far as I’ve been able to tell, many improvements.  For example, I’ve already found updates that cover material I wrote for the course in order to remedy gaps in the second edition.  The fact that the second edition was issued 12 years after the first, and the third edition 16 years after the second, suggests to me that the authors have a commitment to meaningful changes.  This is in contrast to the suspiciously frequent updates to introductory historical and physical geology textbooks.

In the past, I’ve had to modify course materials because of the release of new textbook editions.  This happened recently for one of my other distance education courses.  The process took part of an afternoon and consisted largely of changing out a few page numbers.

Not so this time.  I relied heavily on the textbook when designing the course (why ask students to buy it if they aren’t going to use it?), and incorporated readings and image references throughout the course materials I’d written.  I knew I was in trouble when I read the preface to the new edition and found the phrase “sea-change” more than once.

As I said earlier, the changes are not minor.  Readings I used from the second edition have been chopped up into little pieces and sprinkled throughout the chapter.  Figure 1.42, “(A) Geologic map and structure profile of a medium-sized pepperoni pizza.  (B) Kinematic model of the translation and rotation of the pepperoni,” has moved from page 33 to page 9, becoming Figure 1.9 with an additional “(C) Detail of displacement vectors.”  This means that words like “kinematic,” and “vectors” have come into play much sooner than I would like, and spoiled the gentle introduction to the subject that I had intended.  Whole chunks of the chapter on plate tectonics, including key images, have been excised.  This probably makes sense for this textbook, because the students who use it should have been introduced to the concepts in prerequisite courses, but my students tend to need the background.

My course amendment document is at 4 pages and I am only at the beginning of Unit 2 (of 7) in the theory section of the course.  I feel sorry for the students who will have to use this document to navigate the course until the necessary revisions are implemented.

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