Category Archives: Instructor comments

Grading completed

The final has closed, and the grades for the final have been adjusted according to the “best 20” rule.  ANGEL has done its thing and the grades have been entered into ELION.  For those who are interested, here’s how the grade distribution went down:

  • A and A-: 8
  • B+, B and B-: 15
  • C+ and C: 7
  • Other: 4

Once again, I’d like to thank all the students who participated and made this such an interesting class to teach.  Best wishes to those of you who are graduating, and for the rest, have a great summer!




California groundwater article

Here’s an article from the New York Times today: “Beneath California’s Crops, Groundwater Crisis Grows.

This might make a subject for a blog post.  As well as the specifics of the CA situation, think about the metaphors that the NYT feels it appropriate to use to explain stock-flow ideas to its intended audience.

See also this blog post from Andy Rivkin, which has lots of references for further reading.


“Spreadsheets of Power”

Here is a rather different take on economic modeling (including the kind that went into the Stern Review, presumably).

This article is about the use of mathematics (in the form of economic modeling) to distract and obfuscate – to shut down debate.  My hope in offering this course is that mathematics can also empower.

Probably a blog post or two in here somewhere!


Grading statistics – midterm 1

Here are the grading statistics from midterm 1

Midterm1Some of the compression at the top end is caused by our selecting the best 10 questions out of 12.  But even allowing for that, we have a very bimodal distribution, with one larger group of students reaching an almost-perfect score, another rather smaller but significant group who are having trouble with half or more of the questions, and few in between.


Grading statistics – blog period 1

Grading has finished for blogging period 1.  In this post I’ll give some information about the grade distribution, and comments.

Blogs1Here is a bar chart showing the overall grade distribution for blogging period 1.  Let me break down some of the numbers here.

  • There are 20 students in the D and F area. Almost without exception, these are students who either have posted nothing at all, or posted their initial introduction (required in Week 1) and then stopped.  Because of the best-of-three-periods algorithm that I am using for the blogs, these students still have two opportunities to succeed in this component of the course; I hope they take advantage of it.
  • Among those who did post something substantive, many did not post enough to obtain higher than a “C” grade.  For a “B”, the syllabus requirement is one post a week.  This does not seem too demanding, especially for a class without other homework assignments.
  • Many posts contained simple errors that could be eliminated by re-reading them more carefully: links that do not work, math calculations that do not yield the answer stated, mistakes about units (confusing dollars with cents was surprisingly common – let’s hope students don’t do that in real life!)
  • A quality post does not just contain numbers, but uses quantitative reasoning to advance an argument.  A good way to do this is to make comparisons between different scenarios.  Sarah’s sample post is a good example of this.
  • It was interesting to see so many posts that tried to evaluate some “sustainability”-related change (should I use bottled water?/buy a hybrid car?) in financial terms alone.  Sometimes the “sustainable” approach will save money, sometimes it may not.  I would have liked to see more discussion of the trade-offs that are inevitable in such decisions – I sometimes got the impression that the financial bottom line was going to settle everything.
  • Even in the best posts there was room for improvement in presentation, argument and referencing.  I will be glad to talk in office hours with anyone who wants help working on their blogging skills or crafting a quality post.


Attendance in class

We’ve now had three in-class pop quizzes.  As is explained in the syllabus, these quizzes are used to help verify attendance in class.  To quote

However, a 2.5% per quiz “attendance” score will be awarded to those who are in class and participate in four of the pop-quizzes. Note that there will probably be more than four pop-quizzes during the semester. You won’t know until afterwards which pop-quizzes are being used to verify attendance.

Just to clarify that last sentence: we are recording participation in all the pop quizzes, and at the end of the semester we will randomly select four of them which will be the ones that count for verifying attendance.

With that in mind I took a look at the statistics from the in-class quizzes we have had so far

  • 20 people have been present for all 3 quizzes
  • 10 have been present for 2 out of 3
  • 6 have been present for 1 out of 3
  • 4 have been present for no quizzes (!)

There is no substitute for showing up.

Thoughts about blog posts

So we are more than halfway through the first blog assessment period.  The TAs and I have read through everything that you all have posted.  There are a lot of interesting ideas out there, ideas that, with a bit of thought, could be developed into excellent posts.  (And remember, you can go back and edit your post, until the end of the blogging period, if you want to improve it; the final grade will be based on the final version of your post.) But fewer of the posts are excellent right now.  Here are some suggestions for the future.

  1. You cannot get points for posting if you don’t post.  As of right now, 8 class members have not made any posts at all, and a further 16 have not posted anything beyond the introduction that was required in week 1.  Yes, I know that according to the grading rules, you can in theory make things up in the second or the third blogging period, but it will take practice – practice which might as well start now.
  2. Posts should contain numbers, but should also set those numbers in context.  Too many posts suffer from the “gee whiz” use of numbers (this is a problem with a lot of environmental writing generally, I find): “if we all did this simple thing we could save 3000 barrels of oil a year”.  All well and good, but how does 3000 barrels a year compare to the total amount of oil that “we” are responsible for consuming?  Is it huge in relation to our total consumption, or insignificant? If insignificant, is it worth the time to do the simple thing (whatever it is)? What are the costs of doing the “simple thing”? etc.
  3. Posts should also contain calculations: it’s not a math post just because you quote a lot of numbers from some web site or other. This post for instance tries to do that by expressing energy consumption of different countries in terms of the number of people who consume one MToe/year.
  4. I’d like to see a clearer awareness of the distinction between environmental benefits (accruing to society at large) and financial benefits (maybe to the individual consumer) – I’m thinking of some of the posts about hybrid cars here, for example.  Related, though not the same point, is to make some effort to quantify trade-offs: if putting solar panels on my roof costs me x dollars right now, and saves me y dollars per year using net metering, how many years will it take to pay back my investment?  (This particular example requires some financial math, about the present value of an annuity, that we will cover in the next chapter.)

Okay, that’s enough suggestions for one post!   Remember that I or the TAs are happy to talk about your blogging during office hours or at any other time by appointment…