Day off today, planning sabbatical

Today was a day off for University of California, celebrating Cesar Chavez Day, though the official day for that is next Tuesday March 31.  I did a little undergraduate director work via e-mail, but mostly took it easy today.

Trader Joe’s

I started the day by bicycling to Trader Joe’s to take advantage of their first hour for seniors (I’m over 65 now, so I qualify, though I don’t think I’m at particularly high risk). The setup was that they had two lines—one for seniors and one for others, allowing people to self-identify to choose which line to join.  The cart handles were being cleaned between uses and customers were getting their hands sprayed before being let in.  They were regulating the number of people at a time in the store, but the line moved fairly quickly, as people were not lingering in the store.

Trader Joe’s has always had super-wide aisles, so social distancing in the store was easy.  I quickly grabbed the stuff I had come for (most of my TJ staples: beer, cider, port, chocolate, paper towels, and soap) and checked out quickly so that others could enter the store.  I don’t think I need to go back to TJs for a couple of weeks, as I have at least a 2-week supply now of just about everything that I ever buy there (we got laundry detergent, cereal, and toilet paper a week or two before shopping got crazy).

Mowing lawn

After I got home from shopping (and scrubbing my hands and the doorknobs I’d touched), I got out the electric lawn mower and mowed both the front yard and the back yard.  The grass (and oxalis and wild onions and all the many other plants that make up my “lawn”) had gotten pretty long, but the plants were still soft, young plants, so the mowing went fairly quickly.  I even managed to fill my 40-gallon green-waste container with blackberry vines, ivy, and chunks of the dead rosemary bush.

Having sabbatical  this spring does mean that I’ll probably be able to keep the grass cut this year, for the first time in about a decade.  No 4′-high meadow with 8′ thistles this year!  Removing all the ivy and blackberries, though, is probably beyond me—filling the 40-gallon green-waste container weekly will probably be just enough to keep the current overgrowth from getting bigger, without making an appreciable dent in the 500 square feet covered with with them.

Preparing for sabbatical

I’m going to take this weekend off (sleeping, re-reading fantasy or science fiction books) and on Monday I’ll start working on creating video tutorials for sections of my book. I’m still debating how to do the visuals for the videos: prepared slides, pen on paper with a document camera, white board in front of the computer, or tablet and stylus.

I am not fond of prepared slides as a presentation style, though I know it has become the most common style for STEM lectures, so having a set of slides to bundle with the book might make it more attractive for instructors to adopt.  My lecture style has been more of an improvisational performance, triggered by questions from the students—that will not translate well to videos with no audience, so I’m going to have to develop a whole new teaching style for myself.

I’m looking at a few document cameras on Amazon ($100–$150), though I briefly considered making a stand for my cellphone (which has a 12MP camera) instead.  I think that having a USB-attached camera with a reasonably designed arm will work better with the various software I might use for making the video than trying to jury-rig something with my cellphone, so I’d be willing to invest in the document camera—if writing on paper works for me as a lecturing style.

The closest I’ve come to using that style in the past was in Spring 2000, after I had the bike accident that necessitated removing my spleen.  I had to lecture sitting down with an overhead projector until my ribs healed—I found it much more limiting than my usual large-whiteboard lecture style, as I could not build up an information-rich surface to point back to previous items on, as I had to keep changing pages.  Whatever I do for the videos is going to have the same problem, though, as the screen is a tiny, little window that can only hold one thing at a time.

I’ll probably also have to invest in colored markers if I lecture on paper—I write somewhat more legibly with a broad chisel-tip calligraphy marker.  I’ve only used black calligraphy markers in the past (the Itoya double-header), but I see that the same company makes colored ones in the same style.

I tried a whiteboard in front of my desktop for the last (optional) lecture of BME 51A.  It was not technically very successful—lighting and contrast were problems, as well as the size of the writing on the screen being too small.  I could try a small whiteboard with a document camera, but I suspect that it will not work as well as paper and calligraphy markers.

One big advantage of the document camera is that I can put small objects (like components or breadboards) on the screen easily—I even do that in some of my live lectures.

The most expensive option is to get a tablet computer (e.g., iPad or Surface) and pressure-sensitive stylus.  I’m not convinced that I’ll be able to write all that well on them, and interfacing them to software that let’s me switch easily back and forth between a head-shot camera, a small-parts camera, preprepared images, and the stuff-drawn-on-the-tablet may be difficult.

Of course, if I’m putting together a video, I don’t have the same time constraints that a live remote lecture would have, as I can film each scene separately and edit them together.  Editing takes up a lot of time though, so I’m not sure I want to go that route, rather than recording in one continuous stretch.  (Yes, I know the quality would be better if I spent a lot of time editing, but I’m not sure I have the time to do even quick-and-dirty tutorials on all the topics.)

Another big change for me is that I’ll probably have to work from a script, rather than doing an improv lecture.  That’s because I’ll need to do closed-captioning on the videos if I post them on YouTube, as the automatic YouTube closed captioning is ludicrously bad (see YouTube closed captions are awful), and it takes forever to put in the captioning unless you have a script already prepared.

Going from big whiteboard real estate and an improv style to tiny screens and tight scripting is going to be a big change for me.  It’s a good thing I have six months to experiment with different approaches and don’t have to go live on Monday  like most of my colleagues.

Unexpected consequences

One good consequence of the sudden forced switch to remote teaching is that there has been more discussion of pedagogical tools (Canvas quizzes, document cameras, tablets, zoom, take-home exams, …) among the faculty in the past week than there has been in the previous 5 years.

Unfortunately, all the discussion has been about lecturing and high-volume remote testing, with none about teaching writing, engineering design, or hands-on lab skills, which are the topics that really need attention (but which are probably going to be sacrificed in this quarter’s remote teaching).

Quiz disappointment

Today’s quiz in class was very disappointing for me, and I don’t know what to do differently to get better results.

Yesterday in lab I returned the quizzes from before break and urged students to look through all the old quizzes and rework any questions they got wrong, reminding them that I recycle questions.

In this morning’s class, before the quiz students asked me to show them (again) how to do one of the questions on the last quiz:

Design a voltage divider implementing Vout − Vref = G(Vin − Vref ), where G can be adjusted from ≈ 0.33 to ≈ 0.67 using a 10 kΩ potentiometer. Use port symbols to connect to Vin, Vref , and Vout.

I showed them two solutions—one that I had expected and a correct, but different solution that a student had come up with.

Here are the two solutions: mine on the left and an alternative one on the right.  (There is a third solution, similar to the second one, but with the potentiometer as variable resistor on the lower leg, rather than the upper one, and the two fixed resistors swapped.)

I had already shown them my solution a week and a half ago, right after they took the quiz, and I had posted both solutions on Piazza.  I not only showed the solution, but gave them an explanation of how it worked again and answered some questions students had about it (like why the gain was expressed the way it was with Vref, and why it was even considered a gain).

Right after that I erased the board and handed out the quizzes.  One of the quiz questions was the identical question that I had just worked on the board for them.  I was resigned to this being a free point for them (just like putting their section number on the quiz is a free point, which I use to distinguish those who are absent from those who are present but get no questions right).

But 20 of the students got no points for the question and 15 got only half credit (out of a class of about 72—there were supposed to be 79, but there were 7 students absent).  So almost half the class could not retain for 5 minutes a simple circuit that they should have been able to derive in a couple of minutes and which they had seen at least 3 times already.

Help!  During the last 10 weeks I’ve gone through just about all the ways I can think of to have the students understand voltage dividers and potentiometers, and I’m obviously not getting through to 28% of them (probably more, since the absentees are likely to be in the group that can’t do the problem also).

Does anyone have any useful advice?  (Giving up on the students is not useful advice—I want them to succeed.)

Co-instructor wanted for applied electronics course

I am looking for someone to be a co-instructor with me for the Applied Electronics for Bioengineers course at UCSC next year (January 2018–june 2018).  There are two reasons for my wanting a co-instructor:

• I want to train someone to take the course over from me when I retire (in about 3–4 years).  Right now, I’m the only person who has ever taught the course, and there are no other faculty at UCSC particularly interested in taking it over. My department has no other faculty who know enough electronics, and the EE and CMPE departments are having enough difficulty covering their own courses, so I need to find someone from outside our usual faculty.
• The course is expected to grow to 100 students next year, and I can barely handle the grading load and lab supervision for 70 students this year (71–73 students last quarter, 68 students this quarter).  If I could split the grading load with another person, we would each have a large, but manageable load.  I might be able to hire undergrad graders to do the homework grading, but not the lab reports, which require good feedback on the writing.

I’ll be hiring undergraduates to help answer questions in the lab, as I’ve been doing this year, but I would want the co-instructor to be present for about half the lab sections.  I think that we’ll have 5 sections of 20 students each, so I’d do 2, then we’d do one together, then the co-instructor would do 2.  The total number of hours a week would be about 3.5 attending/giving lectures, 9.5 hours lab, 8 hours grading, for about 21 hours a week.  I don’t know what the pay would be (depends on qualifications on paper), but the pay would probably be meager by engineering standards—I’d guess it would work out to about $40/hour, though it might be more if the lab time is properly accounted for in the pay rate.

If any of my local readers are interested in the possibility of being a co-instructor, please contact me (karplus@soe.ucsc.edu).  If you know someone who might be interested, please pass on the information.

 

Understanding semilog plots

I realized in doing the homework grading this weekend that few of the students in my electronics course had any intuitive understanding of semilog plots (that is, plots in which one axis is linear and the other logarithmic).  I had been assuming that providing the following plot

Forward voltage as a function of current for a 1N914BTR diode.

would let students see that the voltage grows approximately with the logarithm of the current, and that means that a voltage difference corresponds to a current ratio. Very few students got that from the picture, the formulas, or the description in the text. They almost all wanted to pretend that the diode was a linear device with voltage proportional to current (i.e., that it was a resistor), so that a 6% change in current would result in a 6% change in voltage.  The whole point of using the diode was to introduce the exponential non-linearity, so this confusion definitely needs to be cleared up.

I was going to try to explain semilog plots and exponential/logarithmic relationships in class today, but my cold has gotten so bad that I had to cancel class today. That means I have another 2 days to figure out how to explain the concepts. If any of my readers can think of ways to get students to interpret semilog plots correctly, please let me know. I think that the relationships are too obvious to me for me to help students past their misunderstandings—I can’t get far enough into their mindsets to lead them out of confusion.

Writing feedback

In his post Omics! Omics!: 10 Years of Omicing!, which reflects on the influences on his writing, Keith Robison says

The other person who deserves nearly infinite credit for making me think about my word choices is my father.  Sometimes he strays into being a pedant and enforcing rules which have fallen by the wayside, but he did make me think when I spoke and wrote.  I’ve seen some guidelines for helping students that counsel picking only a few major errors to mark, for fear of scarring the psyche of young writers.  Dad didn’t subscribe to that viewpoint in the least, and I’m the better for it.  In high school I treasured getting back a draft with red ink all over it; it’s a service I missed in college and beyond.  That meant he had read it and thought about it, and my work was always better for it.

I think that this attitude is one that we need to see more of, both among students and among faculty. I put a lot of time into trying to provide thorough feedback on student writing, even though I know that it is not always appreciated.  I also know a number of faculty who bemoan the low quality of student writing, but spend almost no time giving detailed feedback so that the students can improve.

There are times for triage—concentrating on the students whose work could benefit most from editing, while providing only minimal feedback to those who produce word salad or whose writing is very good—but I prefer to try to provide similar amounts of feedback for all students.  For the word-salad students, my comments are mainly on sentence structure and paragraph structure, to try to have their writing make sense at least at a local level. The students in the middle get a mixture of different comments from punctuation to overall structure of the paper, while the top students get mainly get comments on trivial little details that can polish their already good writing.