Friday, September 03, 2010


I’m constantly amazed by the phrase “well just change it” when it comes to teaching.  While you can change some things in class instantly (usually impacting classroom management), most lesson related issues can take some time to change.  Like a year.

Lessons go awry for all teachers.  Even the best have some kind of “off day” or a funky transition or just a lesson that didn’t work as planned.  And when it comes to specific lesson plans, a teacher might not be able to do the lesson plan again until the next semester or the next year.  It gives the teacher a nice opportunity to think about what did and did not work, but there is some kind of illusion out there that lessons, even those that have been done well by other teachers, function with the same effectiveness with everyone.  Remember, every classroom has different variables that are constantly changing.

Take for instance my lesson on Monday called “Cleaning the River”.  The lesson’s objective was to teach about Marginal Analysis and government decision-making. The lesson came from the California Council for Economics Education, and I’ve watched it being taught a half-dozen times.  It is a really effective lesson when done right.  Simply put, you take a piece of carpet and cover it with trash in the classroom.  The carpet is a polluted lake.  You ask for two volunteers and have them “clean” the lake into a bag for ten seconds.  Then you discuss how much trash they picked up and how “clean” the lake got.  Then the volunteers clean it again for ten seconds.  Same time, less trash.  Again, how clean should the lake be? Again. Same time, and even less trash.  All the time the volunteers are “paid” for the service of cleaning the lake and the students soon realize that the marginal cost of cleaning the lake eventually outweighs the marginal benefit.  The lake can never be perfectly clean.  It works really, really well.  So I tried it.

It sort of worked for me, but it sputtered around a bit.  I began the lesson a day early by having students list all the services provided by Mendocino County.  Then I told the students that I had 10 units of resource and that the resources had to be prioritized to county services, thus dealing with the issue of scarcity.  Obviously, 35 students could only really agree on some items, so they democratically elected a “mayor” to make the major decisions.  Eventually the “mayor” came up with five priority items and divided the units of resource.  Then I brought out the lake.  I didn’t have a large piece of carpet so I came up with a really large trash bag that I cut down the middle.  It made a really nice big lake.  The result of the lesson?

-First of all, I have a small group of students (only 3 out of 34) that really enjoy being the center of attention and hijacking the class with fairly pointless arguments.  In this case one of the students insisted that contractors never breach a contract because they don’t want to pay extra money.  It’s one of those situations where you want to move on but the “look at me” students are having trouble  letting you.  You want to throw them out but they are being annoying, not “bad”.  I should have had them step outside early on and not doing that made the lesson get off track.

-The garbage bag didn’t work well at all.  On my tile floor it slid all over the place and some of the smaller items of “pollution” (paper shreds and coffee grounds) made a little mess.  Wasn’t that big of a deal, but  it elicited giggles which distracted from the lesson.

-The third round of cleaning involves the idea of need “specialized equipment” to successfully clean the lake, aka a handheld vacuum cleaner.  Carpet and vacuum work well.  Plastic garbage bag and vacuum work poorly and it became an exercise in reigning in the laughter. 

In the end, the lesson provided a decent idea of marginal analysis.  But it was clear that the lesson had little flow, was veering off track on every opportunity, and became a greater bane than a benefit to class time.  Was a total failure?  No, not by a long shot.  But by this point I want a certain vibe and flow to my class, and this new lesson didn’t provide that.  So it was a disappointment that I want to change before I teach it again in January to my next semester of Economics.  Hey newbs, even ten years in things will not always go as planned.  Get used to it and change it for next time.  You won’t have much time to mope about the negativity.  The next class begins in 7 minutes.     

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