Geotechnical Engineering – Assignment 1

Why is my course important?  We’re asked to explain this “to” our students or “for” our students in our syllabus.  Not that I can’t do this, but should I?  Is explaining the “importance” of our class just another example of exerting power over our students, right from the beginning?

Maybe this is another question that we can help and encourage our students to explore for themselves.  I’m envisioning a syllabus and first assignment in an introduction to geotechnical engineering course (a junior-level class) that goes something like this.

Syllabus Intro:  Throw out half a dozen intriguing facts about soil mechanics that will pique the interests of these young civil engineers.  Try to touch on all the major branches of the discipline; cast the net large.  Brief entry-level papers could even be provided as background for the facts for students who want to explore further.  For example:

  • Did you know that expansive soils cause an estimated $13 billion damage to buildings in the US annually, more than the effects of hurricanes, floods, tornadoes, and earthquakes combined (Rendon-Herrero, 2011)?

Assignment #1:  Brainstorm and record the reasons why a knowledge of geotechnical engineering and soil mechanics will be important to you (aside from passing the FE exam).  Use the facts/questions in the beginning of the syllabus as a jumping off point, if necessary.  Also consider the following:

  • If you plan to concentrate in geotechnical engineering, explain why.  What attracts you to the field?  What makes you interested in it?
  • If not, how do you think that your concentration (structural, transportation, etc.) interacts with geotechnical engineers in practice?  How will the content of this course help you with those interactions?
  • Think of this assignment like a journal entry, not a paper.  It will be graded based on the thoughtfulness of the response, rather than the elegance of the prose or the conclusiveness of your argument.

I think an assignment along these lines could really help students think through the purpose of the class and semester before them.  It would be helpful to compile, distribute, and discuss the results with the class and share the student’s various insights with everyone.


A lesson from the farm

Wendell Berry writes in Andy Catlett about a young boy of the same name spending time with his grandparents on their farm.  The youth is gently forced outside on a cold winter morning to help his Granddaddy and a family friend, Burley, work in the barns.  Reluctantly at first, he helps them as they “kept finding ways for me to help” and “let me belong there at work with them.”  As the morning and the work progresses, Andy finds that “I went from reluctance and dread to interest in what we were doing, and then to pleasure in it.  I got warm.”  He realized thankfully that “the men were letting me help sometimes even when I could see I was slowing them down.”

What a beautiful picture of the learning and growing process!  In this case, it’s not “school learning” but more practical work or trade learning on the farm.  Nonetheless, the old men, as teachers, gently led Andy from reticence to pleasure in the task before them.  I believe that is part of our role as teachers.  Our students often come to us forced to take our particular class by the university or their department.  They arrive reluctant and reserved, like Andy in the barn on a cold winter’s morning.  We succeed as teachers when we help our students move from cold indifference to interest and pleasure in the work at hand, whether it be farm chores or calculus or history.

Granddady and Burley wisely chose to simply involve Andy in their own work.  They didn’t sit him down on a bale of hay and lecture to him about the intricacies of building sheep pens.  They didn’t make him muster false exuberance about the work before making him help with it.  The men knew that learning often comes through doing, and pleasure in work/learning often comes through accomplishing a task with an appropriate amount of help.  Even though Andy slowed down their work and made them less efficient (They couldn’t cover as much material??), he was not cast aside as too inexperienced to be involved in the work.

Maybe we need to learn some lessons about teaching from this simple story from the farm.


The power of a crumpled piece of paper

My office mate, who is teaching for the first time this semester asks, “How can I explain the concept of specific surface area (SSA) to my students and the difference between sands and clays?”

For those uninitiated to soil mechanics, the SSA of a soil is the ratio of particle surface area to mass.  Sand particles are roughly spherical and have a small amount of surface area relative to their mass.  Clay particles on the other hand are extremely thin plates with many times more surface are than those in a sand.  For example, a 100 g (4 oz) of some clay may have enough surface area to cover a football field.

We discussed the matter for a few minutes and devised the following demonstration, which my office mate could perform off-the-cuff during class:

  1. Take two pieces of plain paper.  Same paper = same mass.
  2. Crumple one up into the smallest ball possible.  Ask the class to imagine there is no air left inside the ball.
  3. Compare the surface area of the balled up paper (think – sand particle) and the flat sheet of paper (think – clay particle).  The clay obviously has much greater surface area because of its platy shape.  The class could quickly calculate the surface area of each, if desired.
  4. Optional: Throw balled up paper into the class.  Try not to hit anyone in the head.

My office mate’s post-class assessment of the demonstration was positive.  The class was jolted out of “take notes” mode into “something different is happening” mode.  They appeared to pay more attention and really grasp the concept more fully than if a blackboard description had been used.  Score one for the Crumpled Paper.

Bonus demonstration to explain hydrometer analysis and Stokes Law.  Prior to Step 4 above:

  1. Hold the ball and sheet the same distance above the ground.
  2. Drop both at the same time.  The ball will fall to the ground while the sheet floats back and forth, impeded by drag forces that are large in comparison to particle weight.
  3. Ask what is different about this demonstration and the assumptions of Stokes’ Law.
  4. Repeat Step 4 above.