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Goodbye beloved, bad pedagogypublished Apr 8, 2020 3:54pm
But I have clung to analog (paper) stereonets. Every year, I gave students a piece of paper with a photocopied equal-area stereonet, a piece of cardboard backing, a thumbtack, an eraser, and tape, and showed them how to make a sturdy stereonet. Then I handed out the tracing paper and we practiced plotting, twirling the tracing paper around the thumbtack, trying to follow the great circles, going through the complex rituals of plotting planes, poles to planes, and lines. Eventually, I introduced Rick Allmendinger's Stereonet program and we went through it all again digitally, prompting students to ask, "So... um... why did we have to do this on paper?"
Why, indeed? I had to stop myself from saying, "It's good for you!" The question always made me think. It felt important to ask them to use their hands, to rotate the tracing paper, to physically draw the arcs and count out the degrees to plot the points—it felt like this would help them learn.
Here's the thing, though. It didn't, not in this case. The whole thumbtack-tracing paper twirling thing is just a kludge so that you can plot the correct arc by hand. But it introduces a whole slew of misconceptions, including the idea that every plane started with a north strike and rotated to its current orientation. The mechanics of drawing the arc actually detract from the desired learning outcome (using a stereonet to plot and analyze structural data) and instead test students' ability to follow somewhat arcane directions. Digital plotting, on the other hand, builds on their intuition. They type in two numbers, look at what shows up, toggle into 3D mode, and they immediately see that the orientation of the plane matches the way they are holding their hand. Rather than describing over and over again, "OK, now rotate the tracing paper by the strike, ..." we can go very quickly to poles to planes and the higher cognitive level processes, like data analysis.
Compare this with locating yourself on a paper map without use of a GPS device. In this case, the process reinforces the desired learning. You look at the landscape around you, looking for features that you can find on the map. You identify where slopes are steeper and less steep, look for intersections, high points, bends in the river, and use all of these observations to pinpoint your location. You can get better at finding yourself precisely when your GPS can't connect to the satellites or the batteries run out or you forgot it in the car. You can read the map to plan your route: your GPS will not tell you not to walk over a cliff, but you can identify the closely-spaced lines on the map and know not to go there. Both the paper map and the GPS map are useful.
Making paper stereonets—not so useful. I know this. Yet I was so reluctant to give it up. Why?
I finally realized that it was for the most selfish of reasons: I like doing it, and I'm good at it, and it makes perfect sense to me. I like it for the same reason I like drawing all those block diagrams and doing crossword puzzles—I think it's kinda fun. But... "fun" does not make it worth figuring out how to get all of the students the supplies they need to make their own analog stereonet, especially when there is a far superior option already out there.
So thank you, coronavirus, for finally convincing me say goodbye to this beloved, bad pedagogy. And thank you, Rick Allmendinger, for creating Stereonet and continuing to offer it for free, and adding the 3D visualization toggle in recent versions. When students enter the strike and dip of a plane and then look at it in 3D, they say, "Oh!" And they get it. No more misconceptions about rotation, deformation paths that don't exist. Just, "Oh!" And suddenly they are contouring poles to planes and finding fold axes.
Some of my colleagues will undoubtedly disagree with me, and I welcome the discussion. Some may be aware of research that supports one approach or another—please share!
Goodbye beloved, bad pedagogy -- Discussion
Yes, shout-out to Visible Geology - I use that as well!
14288:43726Share edittextuser=888 post_id=43726 initial_post_id=0 thread_id=14288
Otherwise a great post and thanks for the kind words.
14288:43735Share edittextuser=71907 post_id=43735 initial_post_id=0 thread_id=14288
Thank you, Rick - your software is fantastic.
14288:43736Share edittextuser=888 post_id=43736 initial_post_id=0 thread_id=14288
I love stereonets, but I wonder whether they are useful to anybody other than a professional structural geologist. I think we can give them up entirely given that 0.01% of our students will become professional structural geologists.
14288:43737Share edittextuser=888 post_id=43737 initial_post_id=0 thread_id=14288
For what it's worth, my Stereonet program gets downloaded about 35,000 times a year and Stereonet Mobile for iOS gets downloaded around 5000 times a year from more than 100 different countries, so someone thinks it is important.
From the mail I get, it is not just structural geologists who use stereonets: I also hear from archeologists (orientations of artifacts), ecologists (how birds align twigs in nests, ant trails, etc.), geophysicists (can't interpret focal mechanism solutions without knowing stereonets), mineralogists, paleontologists, sedimentologists, and even astronomers. Stereonets are the tool of choice for anyone who needs to visualize orientation data. Fracture orientations are a key parameter in understanding induced seismicity and fluid flow in the subsurface which are incredibly relevant today. If our students all give up and go to biz school then, no, they don't need to learn stereonets but if they remain in any science field, then it is useful.
14288:43742Share edittextuser=71907 post_id=43742 initial_post_id=0 thread_id=14288
Stereonet programs are not secretly rotating pieces of tracing paper inside the computer. Instead they use simple vector operations that are taught in the math courses that we make most of our undergraduates take. We owe it to our students to show them how the math that we make them take is used to do orientation calculations. Thus, the reason for my free structure lab manual (http://www.geo.cornell.edu/geology/faculty/RWA/structure-lab-manual/downloads... and Nestor, Don Fisher's, and my 2013 structural algorithms books.
14288:43743Share edittextuser=71907 post_id=43743 initial_post_id=0 thread_id=14288
I choose the structural geology content to teach in part based on my skills and passion and the critical thinking skills I want them to gain. I introduce them to key concepts around deformation but take into account where most of my students will live and work.
Thanks all: I will use this thread to update my class next year!
14288:43752Share edittextuser=104 post_id=43752 initial_post_id=0 thread_id=14288
In my recent experience, students who struggle with "getting" strike and dip also struggle with recognizing the concept of a horizontal line on a dipping plane, and determine this even qualitatively. This reminds me of the cognitive challenge of the famous milk jug test. And from my limited knowledge of 3D thinking, the basic comprehension and intuitive visualization has to come before the more abstract application, like strike and dip.
Perhaps hours working with paper stereonets does help some students, as do mechanical props. But I like the intuitive insights available with a smart phone app, where the stereonet display varies interactively as a student rotates the phone.
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14288:43758Share edittextuser=271836 post_id=43758 initial_post_id=0 thread_id=14288
Here are just some additional thoughts to consider:
Regardless of the format, doesn't this still require a detailed explanation of how 3D structural features are plotted and visualized on a 2D diagram? The practice of teaching stereonets is like many other geologic concepts, in that, there are instructions and inevitable misconceptions. For instance, having students plot data on a ternary diagram is not void of these same issues. Once students learn to overcome these challenges, however, they can do this with ease. Is that not evidence of learning? Why skip the steps that reinforce problem solving for the sake of a particular outcome or teaching challenge? I have always felt that teaching the process of how to plot, visualize, and communicate 3D information was arguably an important course objective in introductory structural geology courses. Having them critically think about each step is central to achieving that goal. Once they learn how to use the basic tools, students can certainly use the digital version to solve more challenging structural problems and plot larger, more complex data sets.
Have you asked students to work the problems backwards (i.e. from digital to analog)? One could argue that if they truly understand the concept, students should be able to plot the data on the analog version after being taught how to use the digital method. However, it seems like students really struggle or are incapable of doing this, which begs the question - do they really understand how to represent 3D structural data better using the digital method? You are correct, it is very common for students to feel prompted to say- "why did we have to do this on paper?" But it's also common for students to immediately follow up with "why should we learn how to do this if the software will do it for us?" Don't you feel that these questions are more about expediency than students having a vested interest in the learning process? I would certainly agree with Rick's statement- "computer programs run the risk of being viewed as magic if we do not also teach our students how they work."
Anne - you mentioned that it is challenging to figure out how to get all of the students the supplies for their own analog stereonets. The fact that analog steronets can easily be constructed with basic office supplies makes them the obvious choice. They are easy for instructors and accessible to all students. Based on my experience, the Mac version is capable of plotting a 3D visualization (Stereonet3D), but the PC version does not (I could be mistaken). For faculty that use Macs, this is not an issue. However, a fairly large number of students use PCs because they are more affordable. Would this not generate inequities in student learning, especially those student who do not own or use a Mac?
14288:43763Share edittextuser=50309 post_id=43763 initial_post_id=0 thread_id=14288
You are correct, Ken, the Windows version of Stereonet cannot do the 3D plotting. I happen to be killing time in isolation doing a complete from the ground up rewrite of Stereonet and this discussion has convinced me that I need to learn OpenGL so that I can incorporate a 3D view in the Windows and Linux versions. Hopefully, it will be available by summer. Now back to learning about quaternions. Talk about teaching old dogs new tricks...
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14288:43775Share edittextuser=3065 post_id=43775 initial_post_id=0 thread_id=14288
Just a brief note for anyone still reading this thread that Stereonet 11 for Windows, Mac, and Linux can now display a 3D view which means that students on any platform can take advantage of what Anne has written about. This discussion is what inspired me to learn openGL and add it, so thank you Ken for pointing out the potential inequity. The program can be downloaded from:
It's probably too late for this semester but who knows what the Fall will bring...
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