# Gas station without pumps

## 2020 March 25

Filed under: Circuits course — gasstationwithoutpumps @ 21:26
Tags: , ,

I’ve finally finished my grading for Winter 2020.  It took me longer than usual—about 2 hours per paper.  Partly this was because I had some trouble focusing on work with all the COVID-19 news, partly it was because I kept getting distracted by undergrad-director duties (cancelling lab courses for next quarter and trying to get two additional courses funded and staffed with TAs), and partly it was an attempt to give the students more thorough feedback than usual, because some of them will not be taking the second half of the course.

We decided that any student who is graduating in Spring 2020 can petition to replace a cancelled lab course (like the second half of my course) with a different course that they can take (or have taken).  Reading those petitions has been one of the undergrad-director duties that has been taking up my time.  So far, most of the petitions have been acceptable—students have given pedagogic justifications for their choices that made the substitutions reasonable, even if not covering the skills that the cancelled course would have taught.  In a few cases, I’ve suggested that students revise their petitions, particularly when they’ve proposed replacing a 5-unit course with a 3-unit one.

I also ended up letting 17 of the 50 students in my course switch from graded to pass/no-pass, which is not usually something faculty can offer. Because Winter 2020 was such a disaster at UCSC (between the wildcat strike and the COVID-19 shutdown), faculty are allowed to assign P/NP grades this quarter, even if students didn’t sign up for them.  The programs in the Baskin School of Engineering usually require that all courses in the major be taken for a grade, but the BENG/BINF/BMEB majors are being allowed to have P/NP grades for Fall 2019 and Winter 2020 even in major courses.  I let the students choose whether they wanted the grade they earned or a P/NP for my course, though they only had about 3 hours to make up their minds.

The grades were lower than usual this quarter, even after I lowered the cutoffs for each grade.  Because the quarter was so stressful for students, I lowered the cutoffs much more than I usually would have.  This may come back to bite me in the fall, as there were three students who were not really doing passing work (should have gotten C-), who I passed anyway.  If they have the same sloppy approach to their work in the Fall, they will not pass BME 51B, causing their lab partners and me a lot of grief in the process.

In some ways the reports this year were better than previous years—there were fewer incorrect symbols for the NPN phototransistor and the bandpass filters were generally ok. But in some ways they were worse—there were only a few students who understood what the log-transimpedance amplifier did and reported its gain correctly, and there were many who had inconsistent component values in different schematics or between the schematic and the main body of the report. A lot of students keep making the same mistakes in report after report—apparently they never read the feedback I spend hours giving them or ignore it as unrelated to anything they do.

The writing quality remains mostly bad—though perhaps that is not so unusual for this point of the course—I think that the second quarter of the course is when most of the students begin to pay attention to the writing feedback and working on improving their writing.  There were a few students whose writing was ok on the Lab 6 reports, though nothing extraordinarily good.

One thing I’ve noticed every year in the pulse-monitor lab is that a lot of students attribute the 60Hz noise to the fluorescent lighting or to electromagnetic interference, rather than capacitive coupling. But no one has done any tests to see which was the true source. I should do some tests (black out the phototransistor with electrical tape, but keep my finger on it vs. expose phototransistor to fluorescent light with no capacitive source nearby, contrast the fluorescent light to steady light, …).

One problem will be finding old-fashioned 60Hz fluorescent lights at home—I don’t know that we have any left, as I’ve replaced all the oldest fixtures with LED lights. We still have some compact fluorescent bulbs, but they generally have high-frequency electronic ballasts to avoid the 60Hz flicker.I might have to sneak into my office at work to do the tests, if all the lights at home have higher-frequency modulation.

I may also have to do tests with a normal transimpedance amplifier, rather than a logarithmic one, as I want to see the fluctuating current added to the DC light value, rather than looking at ratios of current as we do for looking at the opacity of the finger. A fixed additional current would result in very different voltage fluctuations with different DC light levels, if I used the log-transimpedance amplifier.

## 2020 March 17

### My wife’s new blog

Filed under: Uncategorized — gasstationwithoutpumps @ 21:34
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My wife’s school has been closed (as all schools have been locally), and has moved to remote education.  My wife is trying to replace as much of the library time as she can with a new blog: Spring Hill Library. If you have preK–6th graders at home, you can safely point them to her blog.

I helped her produce her first video yesterday (using iMovie, because Premiere Elements seemed too complicated for the simple task needed), and I helped her set up her first blog tonight. She plans to do a video a day and several blog posts a day for as long as the school is closed (which probably means the rest of the school year).

I may start blogging more often again myself, as I won’t be teaching the second half of my electronics course until Fall. The logistics for running the lab remotely were a bit too daunting for the BELS staff and me, so the lab was delayed until Fall quarter (and I’m swapping sabbatical quarters, taking sabbatical at home this Spring instead of next Fall). If we are still forced to be doing remote education in the fall, at least there will be time to figure out the logistics far enough ahead to be prepared.

Today I should have been grading, but I spent most of my time doing tasks as undergraduate adviser: faculty meeting, updating proposal for our new major, informing students of cancelled lab courses and increased capacity in other courses, trying to get additional courses scheduled to start on March 30, getting approval for our plans to let students substitute other courses for the cancelled lab courses (if they are graduating in Spring 2020), approving student petitions for substitutions, trying to get independent-study forms to not require wet signatures, …

Despite being on sabbatical for Spring, I’ll continue with my administrative tasks as undergraduate director and as a member of the Committee on Courses of Instruction.

I do have to get back to grading tomorrow, as I still have 24.5 design reports still to grade in the next week, and they are taking me about 2 hours each to grade. My wife and I will probably be taking turns on the big-screen iMac, though, as neither the video creation nor the grading work well on the 11.5″-screen laptop.

## 2018 April 1

### Starting new quarter

Filed under: Circuits course — gasstationwithoutpumps @ 17:20
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Tomorrow the new quarter starts, and I hardly feel like I’ve had a break—I was grading continuously through Monday, working on my book through Friday, and setting up Canvas with all the assignments today. I also spent several hours this week reading course syllabi and student petitions for the Committee on Courses of Instruction meeting that is tomorrow afternoon and a little time reading senior thesis proposals from students wanting to start senior theses next quarter.

It probably doesn’t help that I’m on the third week of a cold—it has settled down to being a minor cough, but it is still making me more tired than usual and interfering with my sleep (the cough is worse when I’m lying down).

There is a new draft of Applied Electronics for Bioengineers posted—those who have already bought the book should have gotten an e-mail about the free update.  The minimum price for the book has gone up by 1¢, as Leanpub now has a \$5 minimum, and I had set my book at \$4.99 minimum.  There are not many changes this time, because I did not have a lot of writing time last quarter:

• Beefed up the chapter on lab report guidelines.
• Many typo and minor wording fixes (mainly ones reported by students in class).
• Replaced Waveforms 2015 references with Waveforms 3, due to name change by Digilent.
• Added paragraph to thermistor lab about doing design around standard parts.
• Also added specific discussion of using parallel resistors for current sensing in power-amp lab.
• Added the missing section on high-pass active filters.

By being somewhat generous on my grading for the final lab report, I managed to keep the number of failures for Winter quarter down to two—one flaked so much that all five labs had resulted in the partner requesting doing separate lab reports and the other did not do the last lab.  This is about the usual failure rate (2–3%). Still, I was not happy with how many C grades I had to give—I’d like to see a higher distribution Spring quarter.

Several of the students in my course had previously taken EE101 (circuits) or were taking it concurrently.  I checked, and there was essentially no correlation between the EE101 grade and the grade in my course (Kendall tau correlation about -0.03 for not-taking/taking and +0.07 for grade among those who took—neither is a statistically significant relationship with p-value>0.64).

I think that what would make the biggest difference in the grades is better writing from the students—many of the lab reports were a struggle to get through, with poor organization, poor paragraphing, poor grammar, poor word choices, poor punctuation, and poor formatting.  Only about 10% of the class was writing at a level I would consider acceptable for college students, and I’ll be stressing writing more in Spring quarter.

The grading last quarter was stressful, and I expect it will be again this quarter.  Grading at home during finals week resulted in me putting on five pounds—I kept rewarding myself with snacks after getting through another couple of papers.  I’m hoping that I can get the students to write a little better and a little more tersely this quarter, so that the grading will be less stressful (and I can take the weight off again).

I’m hoping that I can convince more of the students to get out of answer-getting and point-scoring mode (see Just scoring points) on the quizzes and rework any problems they get wrong—I’m tired of asking essentially the same question in quiz after quiz and having students still miss it.

## 2017 April 11

### Co-instructor wanted for applied electronics course

Filed under: Circuits course — gasstationwithoutpumps @ 22:04
Tags: ,

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.

## 2016 April 4

Filed under: Circuits course — gasstationwithoutpumps @ 22:44
Tags: , , ,

I spent all day Sunday grading the first set of lab reports.  I was expecting 24 reports of about 3 pages each, but I got 25 averaging about 5 pages each.  I think that the reports were a bit better this year than at corresponding times in previous years, but I did not get my grading done until almost midnight Sunday night, keeping me from getting much else done this weekend.

(I did manage to get my hair cut and to build a new strobe stand with room for 20 of my LED boards, which should give 1800 lumens during the flash. With a duty cycle of only 1/65, I don’t think that I need heat sinks on the boards for the strobe, as the average current should be only 40mA, though the peak current will be about 2.6A.)

In class on Monday, I gave students some group feedback on their writing, plus a couple of $\LaTeX$ pointers, then took questions, some of which were about writing, but most were about the optimization of the fixed resistor in the voltage divider for the resistance-to-voltage converter in the thermistor lab.  I showed them how to set that up, but did not try to solve it in class.

After class, when I was making up the key (redoing all the problems—I don’t like just looking up results—refreshing my memory on how to solve the problems by resolving them is best), I ran into a little trouble doing the optimization. I used to be able to just ask Wolfram Alpha to solve the differential equation, but their newer parser seems to be much harder to convince to do anything.  I eventually gave up and used a cruder tool to just take the second derivative and solved for the resistance by hand.  That was faster than the time I wasted trying to get Wolfram Alpha to do anything useful.  (I suspect that they have deliberately crippled it, to make people pay for Mathematica.)

Monday afternoon and evening (from about 1:30 to 7:45) was spent grading the first pre-lab homework.  Again the results are a little better than previous years, but there were 9 prelabs fewer than I expected (3 students have dropped already and 6 did not do the prelab).  I hope that those who did not do the prelab were just confused about when it was due, and not starting a trend towards coming to class and lab unprepared. I also hope that no more students drop—this class is not a weed-out class, though it is a lot of work.

Back in January, Mike wanted to know where I ended up doing my grading. Sunday I did my grading in my breakfast room, with the laptop on the floor where I could get to it if I really needed to look something up, but where it was not a constant temptation to goof off.  On Monday, I worked in my office on campus, where the e-mail was a minor distraction that I checked between problems.  (For the prelabs, I graded the entire stack for problem 1, then the entire stack for problem 2, and so forth.  This makes for more consistent and faster grading than grading a student at a time, but it would be faster still if the students didn’t put their answers in random order on what they turned in.) I’ll probably continue with weekend grading in the breakfast room and prelab grading in my office until the distractions get to be too much—then I’ll look for a coffeeshop to grade in.

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