Gas station without pumps

2015 May 31

Confidence and not opting out

Filed under: Circuits course — gasstationwithoutpumps @ 09:06
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In the Geeky Mom blog, Laura Blanken, Computer Science Chair at The Baldwin School, a K-12 all-girls’ school in the Philadelphia suburbs wrote about The Confidence Code by Katty Kay and Claire Shipman (full article at Women and Confidence).

They found one study where men and women were given a test on 3D shapes. The men outperformed the women significantly, which some might think revealed a deficit in women’s spatial reasoning ability. A closer look at the results, however, showed that the women didn’t even answer a significant number of the questions and that’s where the difference in performance lay. They gave the test again, and this time, they told everyone they couldn’t leave an answer blank. When the results were tallied this time, the women performed as well as the men. When women try at most things, they do just as well. This result says to me that making things that people are afraid of mandatory might help eliminate the gap in performance between women and men. And yes, I’m thinking about Computer Science, but there are other things as well.

In my courses, I have not noticed a difference in achievement between men and women, but I have noticed some differences in confidence, though the sample sizes are small enough and the observations informal enough that it could all be biased observation.

I wonder whether the difference in willingness to put down answers that are not confident is part of the reason that the SAT removed their correction for guessing and effectively put in a penalty for leaving answers blank instead.  The effect would initially be to provide a boost for boys (who apparently are more willing to guess), but might eventually lead to more guessing by everyone as students got test-taking training telling them not to leave any answers blank.

The suggested intervention in the Geeky Mom blog is akin to one of the techniques in Teach Like a Champion by Doug Lemov: No Opt Out (Technique 1 in the first book, but 11 in Teach Like a Champion 2.0). While that might work on exams, I don’t think it is enough in the classroom, as it presupposes that you can get the students to participate in the first place. I think that it needs to be combined with Cold Call (technique 22 or 33, depending which edition of Teach Like a Champion you have).

I started this quarter doing a fair amount of cold calling, but by the end of the quarter I am doing very little—there were too many students who were not even willing to guess, and applying No opt out after cold calling was taking up a lot of time without having discernible good results for any of the students. I still do a little cold calling, but only on very easy questions (half the questions in the electronics class are answered with a voltage divider).

It bothers me that at the end of the quarter, I still have students unable to do the simplest design problem (sizing a DC bias resistor for a microphone, because they can’t apply Ohm’s Law coherently: they pick a random voltage in the system, rather than the voltage across the resistor). It isn’t even a matter of transference or dealing with unfamiliar problems, as we’ve done the same problem in labs and in class several times, but some students are still forgetting that there is a voltage across the microphone. It is as if they wipe their minds every week, and start fresh with no memory of anything they have done before.  I don’t know how to reach these students.

I suppose I could give them hundreds of almost identical problems so that they could, eventually, do that problem by rote, but there is no value in that. What I want them to learn is to figure out how to solve simple problems, not how to invoke rote procedures or ritual magic.  But if they can’t solve even the simplest problems after attempting the problem and being helped through the solution a dozen times, I don’t know what to do.

I do have a lot of students still who seem to believe that science and engineering are ritual magic: they hope to give the right incantation (“By Ohm’s Law” is a popular one, and “we calculated” is another), put down a random number copied from another student, and get full credit. I think that some of their other classes have trained them in this—biology classes are full of vocabulary tests where getting the right phrase is all that counts (understanding it is entirely optional) and physics and chemistry classes are full of homework and tests that are graded on “the right answer” with little attention paid to how they student got it (copying works well in those situations). I want to see their reasoning—what assumptions they made and how they applied Ohm’s Law (or whatever other principle is involved) to get their answer.

Copying does not work well in my electronics class, because the correct answers are not unique, and somewhat arbitrary design choices affect the correctness of other choices. For example, the correct size of the DC bias resistor for the microphone depends on the power supply voltage and on the operating point chosen for the microphone, both of which may be somewhat arbitrary. There are reasonable justifications for almost any size resistor from 2kΩ to 33kΩ, so there isn’t a “correct answer” that can be checked off—the reasoning behind the choice is the entire point of the exercise.  But I’ve had students try to size the resistor without choosing the power supply voltage (a sure sign of copying) or behaving as if the voltage across the microphone was 0V (inconsistent with the current they assumed through the microphone). They spent a full lab day measuring the current-vs-voltage characteristics of the microphone, so it can’t be that they have no idea that the current and voltage are related. Or wait—they already turned in that lab, so it is something to be flushed from memory and never thought of again!

Some days I despair of the future of engineering in the US—way too many of the students passing engineering classes are still incompetent as engineers. And I’m at a highly rated R1 university—I hate to imagine what it must be like at less selective schools. At least I get a few good students each year, and the pleasure of teaching and inspiring them can compensate for a lot of the frustration of not getting through to the students at the bottom of the class.

It is a good thing that we get away with only a small fraction of our workforce being competent, because that is the reality we live in.


  1. Very sad and a little bit confusing. Don’t the students need to know the material you are teaching? Or is the issue that many students are taking the course for resume building/transcripts/requirements and thus don’t need to know how to make the measurements? Are they competent in some other area?

    I’m hoping for some reassurance that the engineers building all the things I use aren’t incompetent (and, thinking they can’t be, ’cause lots of things actually do work).

    Comment by bj — 2015 May 31 @ 18:03 | Reply

    • Most of the students are taking the course only because it is required. It is the first and last course they will take in electronics. Many think that they are competent in another area (molecular biology), though I hear from the faculty teaching the wet labs there that some of the same students who are doing badly in my class are also doing badly in the wet lab. Many can’t compute DNA concentration, scale a protocol, make decent records of what they do in the lab, or think about what their results mean—they can generally follow explicit instructions as long as they don’t have to think. I fear they are doomed to be low-level technicians unless they somehow learn to think about what they are doing.

      I think that a lot of engineering management these days is trying to make reliable products when only a relatively small fraction of your engineers are competent—you put together a big team in the hopes of getting enough competent people to carry the dead weight. One reason many start-ups are initially so exciting is they put together small teams of competent people that can get a lot done—but those teams usually get diluted once the company starts having some success, and the company has no idea how to deal with run-of-the-mill teams whose productivity is so much lower than their initial team.

      Comment by gasstationwithoutpumps — 2015 May 31 @ 18:11 | Reply

      • A thought about reaching some (never all) of those students: Maybe you can make your class more relevant by connecting the auxillary skills (compute concentrations, record what they did) to their other classes with a “profs in molecular biology tell me …” anecdotes about the basic skills kids learn in your class that help them get ahead.

        But don’t discount the possibility that all they want is a low level technician job that happens to require a college degree. They probably think it pays $100,000 / year.

        And I’ll have to remember to talk to my brother about the ratio of competent engineers to drones. I seem to recall him saying that a large fraction of them just want to be told what to do.

        Comment by CCPhysicist — 2015 June 3 @ 20:32 | Reply

        • a large fraction of them just want to be told what to do.

          Yes, basically. The point is most people just want to have a well-paying job and would like that job to be as non-demanding as possible of their CPU cycles, energy, and time; being a corporate drone is ideal for them. It’s the job vs career mindset I see a lot; the job is a necessary evil, and presumably everything outside of it is life.
          As a professor, you love what you do, and then see these kids going through the motions while nominally getting the same education that got you all fired up and curious. It’s hard to make peace with the fact that they all have these great opportunities and will do nothing with them.

          In my large sophomore/junior class on electromagnetism, full of middle-class American kids, the only person who knew that the integral of 1/(1+x^2) is arc tan was a young woman from a small country in West Africa. Everyone else was whining how calculus was aaaaaages ago and they forgot (hint: it was aaaaaaaages plus 20-odd years for me). Shame on all those kids who have had a cushy middle-class upbringing and will do nothing of note with it.

          Comment by xykademiqz — 2015 June 4 @ 15:41 | Reply

          • I confess that I don’t remember a lot of the integrals that I learned back in 1971, because I didn’t use them much after about 1982. But some of the trivial ones (like e^x and x^n) stick with me, and I still routinely use things like e^(i w) = cos w + i sin w. It doesn’t bother me if students can’t remember factoids (like tables of integrals or trig identities), but the students who can’t set up simple equations or solve simple linear equations—they bother me. And students who can’t look up the trig identities they need in a few seconds also bother me—it’s fine to dump your memory if you can refetch the information and use it when you need it, but if you don’t have any way to retrieve the information, then dumping is not a good strategy.

            Comment by gasstationwithoutpumps — 2015 June 4 @ 16:18 | Reply

  2. “flushed from memory” Yep. First learned about that a decade or so ago in a rambling discussion where a student mentioned that he didn’t plan to burn his notes from this class. (They had an annual note-burning ceremony every spring in HS and continued it in college.) Probably should revive my blog and write about stuff like that, because I take it for granted but a lot of people don’t know about it.

    The “it” is what I called a failure to comprehend the CONCEPT of prerequisites (or required courses). Most of what I wrote is tagged with prerequisites and the very first (newest, from 2010!) article is pretty relevant.

    I had always made a point of connecting current work to future work and topics in other classes (like calculus), but redoubled my efforts to find out what students actually use in their later classes so I could use those as examples. However, they don’t believe me. What really works is to get former students to drop by and talk. They listen to other students.

    Comment by CCPhysicist — 2015 June 3 @ 20:24 | Reply

  3. Sometimes I worry that what we consider normal (solving new problems) is too high of a cognitive demand on the average brain.

    Comment by bj — 2015 June 5 @ 08:08 | Reply

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