Repetitive instruction; e.g., spreadsheet modeling of geomorphic processesBill Locke, Department of Earth Sciences, Montana State University

Premise: Successful instruction (that is, successful learning) requires repetition: “Nobody ever learned anything the first time”. Thus anything worth teaching is worth repeating so as to pass from exposure to familiarization, to competence, and finally to mastery. I follow that mantra in spreadsheet modeling of earth surface processes, as described below. Note that all projects require in the write-up a discussion of the strengths, weaknesses, and assumptions of the particular model.

Module 1 – SCARP1: Exposure to spreadsheeting Module 2 – SCARP2: Exposure to modeling and scarps and familiarization with spreadsheeting

Module 3 – LONGPRO: Exposure to modeling of streams, familiarization with modeling, and competence in basic spreadsheeting

Module 4 – GLACPRO: Exposure to modeling of glaciers, competence in modeling, and mastery of basic spreadsheetingPremise: most first- and second-year college students

know what a spreadsheet is but few have actually used one beyond basic applications such as balancing a checkbook.

Goals: apply the spreadsheeting skills learned previously and learn spreadsheet functions like conditional expressions and random number generation. Exposure to the principles of modeling including articulation, translation to a logical (i.e., computer) formulation, and implementation in the Excel™ environment.

Goals: expose students to basic spreadsheet functions including formulas, copy-paste and smart-copy, and to the principles of graphical display, including 2-D, 3-D, font, line weight, and color. Also – expose them to the different types of modeling: conceptual, numerical, and physical models versus simulation.

Premise: to students, modeling appears to be something that others (“experts”) do – models are magic black boxes that should be viewed either with complete confidence or total distrust. The way to overcome this feeling is to do it yourself!

Premise: stream evolution is a phenomenon that is difficult to study because of the effect of complexity, time and extreme events, however – streams can be modeled to help understand variable interactions.

Premise: modeling can be used by a junior-level class to address a real-world problem in a way that generates an unknown (publishable?) outcome.

Goals: apply the spreadsheeting skills learned previously. Build competence in modeling by again viewing the model in terms of data, assumptions, and calculations. Exposure to glacial modeling and to research through modeling by the generation of a (potentially) publishable class project.

Goals: apply the spreadsheeting skills learned previously. Familiarization with modeling (especially with required assumptions). Exposure to the problems and advantages of modeling as a tool to understand stream behavior

Figure 1

A)Annotated (faculty) example of 2-D X-Y graph.

B)Example of low-quality student work showing3-D Line (“ribbon”) graph Note VE, white space, labels...

C)Example of high-quality student work showing humor and awareness of value of life-like graphical display.

Problem: extend a simulation model (a 3-point running mean) laterally, mimicking the effect of time. Graph your results in a compelling fashion, considering graph style; font style, size and color; line pattern, weight, and color; title, date and authorship, and legend and annotation as necessary. Does your “model” behave like a real scarp: why (not)? How would you write a “real” scarp model?

Problem: evaluate a numerical model of scarp evolution [includes erosion/deposition dependent upon local slope and “erosivity” – a factor that represents the ratio of driving to resisting forces]. Apply that model to a real-world problem by writing the problem in English, rewriting it to terms a computer can understanding, and implementing it in Excel™. Graph your outcome persuasively.

Problem: measure bed caliber and assume a formative discharge [Q2, Q10, Q50...], then calculate the bedload caliber and flux required to generate an equilibrium longitudinal profile that matches (±10m) the observed long profile of Middle Cottonwood Creek. [NOTE: can be done elsewhere as well!]The problem requires juggling several variables – it is hard enough that only about 40% of students succeed in matching the profiles without breaking rules (e.g., caliber increases downstream…)

Problem: model a former glacier draining the designated mountain range by recognizing the former terminus and recording valley floor elevations with distance up-ice. Graph your model and color the posted map to reflect the former ice extent. Include all glaciated tributaries. Negotiate ice divides with adjacent groups. Consider the work of the entire class and discuss the controls on former ice extent.

The class has modeled former ice cover on the Front Range, Yellowstone NP, San Juan Mountains, Uinta Range, Bitterroot Range, and several others. Two of these have seen publication.

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Scarp Evolution ProfileCary Woodruff & Raymond Hua

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Scarp Evolution Figure 2

A)Annotated (faculty) example of 3-D X-Y graph showing ΔE with time.

B)Annotated (faculty) example of 2-D X-Y graph showing first derivative.

C)Example of low-quality student work showing 3-D ribbon graph of a complex fault scarp evolving. Note VE, spacing, labels…

Figure 4

A)Class reconstruction of LGM Wind River Range ice cap.

B)Profile across LGM wind River ice cap. Note anomalous basal shear stresses! [This work deserves, but has not seen, publication.]

Figure 3

Faculty example of successful model. Note comments re: student reversion to type!

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NOTE: All models described above are available through the SERC Quantitative Skills web page: http://serc.carleton.edu/quantskills/ - search “spreadsheet modeling”.