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2012 August 31

All about circuits, a possible supplemental text

Filed under: Circuits course — gasstationwithoutpumps @ 22:54
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I’ve been dipping into All about circuits, a free electronic textbook written (mostly) by Tony R. Kuphaldt, as a possible textbook for the circuits class.  I like that it is free, as that makes it much more likely that students will have ready access to it (many decide not to buy expensive texts, and end up trying to borrow them from friends).

The format, as 100s of HTML files, is a bit awkward to read, but fairly easy to search with Google (by adding “site:allaboutcircuits.com” to the keywords ins the search box), so indexing is not really an issue.  The book starts at about a middle-school level, but gets up to the beginnings of circuit theory (Thevenin’s TheoremRC and L/R time constants, Reactance and impedance—R, L, and C, …).  The Operational amplifier chapter looks usable, though it does not have a design focus—circuits are presented as almost magical rather than carefully analyzed from first principles (as is done in more theoretical circuits books) or from design rules of thumb (as is done in books like Horowitz and Hill).

I think that All about Circuits can be a good supplemental text for students who need something at a lower reading and math level than Horowitz and Hill, for review of physics electricity and magnetism concepts, and to fill in gaps in prior education (such as complex numbers).

I don’t know that I want to use Horowitz and Hill as the main text, though, as it is pretty expensive for such an old electronics book. I wonder if there is another free book that is somewhat higher level than All about Circuits that can be combined with it to make a textbook at the right level for the range of students expected in the class.

I think we may need a more mathematical presentation of some of the material, if the students are to be able to continue into later electronics classes. This may not matter, because the chair of the EE department has made it pretty clear that no subsequent electronics course would use this course as a prerequisite, and that students would have to take the “real” circuits course in order to take any further electronics courses.  Of course, if he holds to that for the bioelectronics class, then he’ll have almost no students in that class, since few if any of the bioengineers will subject themselves to the dry, repetitive linear algebra manipulations of the standard circuits class in order to take a bioelectronics class that doesn’t even include a lab component.  If we get to teach our applied circuits course, we should be able to convince the professor creating the bioelectronics course to accept it as a prereq in place of the standard circuits course.

Physics C: E&M curriculum for year and Chapter 13 homework

Filed under: home school — gasstationwithoutpumps @ 14:28
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I’ll be homeschooling my son in calculus-based physics again this year, using the Matter and Interactions book.  The school  year has started for him, so now I have to put together a schedule for finishing the book this year. I want him prepared  for the AP Physics C: Electricity and Magnetism test in May. We never got around to Chapter 13 last year on thermodynamics, so I’ll tack that onto the beginning of this year’s schedule.

It looks like I have 34 Tuesdays to cover 568 pages, which is about 17 pages a week.  Assuming that each chapter’s length is roughly proportional to how much time it takes to cover it, I’m planning on

Chapter pages weeks Finish by
13 41 2 Sept 11
14 31 2 Sept 25
15 44 3 Oct 16
16 36 2 Oct 30
17 46 3 Nov 20
18 41 2 Dec 4
19 42 3 Jan 1
20 42 2 Jan 15
21 63 4 Feb 12
22 50 3 Feb 26
23 38 2 Mar 12
24 55 4 Apr 9
25 40 2 Apr 23

Chapter 13 homework—due 2012 Sept 11

13P19, 13P20, 13P22, 13P26, 13P27, 13P28, 13P32

We should probably go over the first three problems on 2012 Sept 4 and do a gas pressure lab of some sort (probably pressure and temperature measurements).  I bought some physics toys last spring that may be suitable for the lab.

 

EMG video

Filed under: Circuits course — gasstationwithoutpumps @ 10:38
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I just got pointed to a video that seems relevant to the EMG/EKG lab:

For those without the patience to watch a 76-second video, it shows the use of 20 EMG channels from skin electrodes being used to control musical instruments (mostly percussion).  It probably takes some practice to be able to control each of the muscles independently with enough precision to play music, as the muscles involved are mostly large ones.

This video might be a good one to show as an introduction to the EMG/EKG lab.

Online physics—what about labs?

Filed under: home school — gasstationwithoutpumps @ 04:31
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I’ve often wondered how online courses handle labs.  Of course, in some fields (like computer science) the tools needed for doing labs are ubiquitous, and there are few safety concerns for doing the labs on your own.  In other subjects, like organic synthesis in chemistry, the safety equipment and supervision needed for many of the labs makes it imperative that students do the labs in a supervised setting.  In between are subjects like introductory physics and electronics, where it is possible to simplify the labs and use low-cost equipment to get most of the benefits of a lab course in a home setting.  More advanced topics in both fields start getting into equipment needs that exceed what an individual would want to buy or be able to borrow.

Since I’m home-schooling my son in calculus-based physics (so far we’ve mainly done mechanics, but this year we’ll be doing electricity and magnetism), I’m particularly interested in how online physics courses handle labs, looking for ideas that I can adapt for our own non-online course.  I found a recent paper by Ann Reagan, published by the Washington Academy of Sciences Online Introductory Physics Labs: Status and Methods.  This paper is a survey of online physics courses, attempting to find out what is being done.

In the intro, they reported 5 goals as desirable for physics labs, based on a position paper by the  American Association of Physics Teachers [“Goals of the Introductory Physics Laboratory,” American Association of Physics Teachers (AAPT), The Physics Teacher, 35, 546-548 (1997)].  Unfortunately, that paper is hidden behind a paywall.  At first I thought that even my university library’s subscription was unable to penetrate the paywall, but that was just bad implementation of the paywall, and I was eventually able to get a copy by editing the URL.  The goals in the original paper are listed as

Summary of Introductory Physics Laboratory Goals
I. The Art of Experimentation: The introductory laboratory should engage each student in significant experiences with experimental processes, including some experience designing investigation.
II.   Experimental and Analytical Skills: The laboratory should help the student develop a broad array of basic skills and tools of experimental physics and data analysis.
III. Conceptual Learning: The laboratory should help students master basic physics concepts.
IV. Understanding the Basis of Knowledge in Physics: The laboratory should help students understand the role of direct observation in physics and to distinguish between inferences based on theory and the outcomes of experiments.
V. Developing Collaborative Learning Skills: The laboratory should help students develop collaborative learning skills that are vital to success in many lifelong endeavors.
Many of the goals are not explicit in traditional laboratory programs. However, the American Association of Physics Teachers believes that laboratory programs should be designed with these five fundamental goals in mind.

I’m in agreement with these goals, though the “collaborative learning skills” will be somewhat limited with just my son and me working together.  (Last year we had another student in the course, but he graduated high school and went off to Pomona.)  I think that the collaborative learning aspects are the least important of the five goals for an intro physics course, as I’ve outlined in other posts on group work.

The first observation in Reagan’s paper is that online physics courses with labs are still fairly rare.  Only about 10% of colleges offered introductory physics online, and 40% of those required the labs be done on-site at the campus, often as intensive weekend or week-long “boot camp” experiences.  That leaves only about 6% of intro college physics courses as attempting fully off-site lab courses.  The paper identified 4 different approaches:

  1. Video analysis of instructor-provided videos.  The instructor designed the experiment, set up the equipment, performed the experiment, and recorded the results on video.  The students used video analysis tools (like the free tool Tracker, which I’ve made some modifications to) to extract data from the experiment and do the data analysis. (Meets goals III and IV, and the data analysis part of II.)
  2. Virtual experiments using simulations (like the well-regarded PhET simulations) are done, with the students interacting with a model of the phenomenon being studied. (Meets goal III and the data analysis part of II, has a flavor or goal I, but without real-world constraints.)
  3. Home experimentation using  loaned equipment or low-cost lab “kits”. (Meets goals I through IV, though only a limited set of the tools of experimental physics will feasible).
  4. Remote labs, where students interact with real equipment, manipulated remotely through the Internet.  (Meets goals II through IV.  Adding goal I would require extremely clever design of the remote operation interface.)

Of these approaches, only the on-site lab and the home experimentation provide the ability to meet the full range of goals. The colleges seem to agree as only 4 of the 400 sites surveyed had simulation-only “labs”.

My own experimentation with home-built equipment last year (see Physics posts in forward order for the full set of posts) leads me to believe that simulation is a terrible substitute for physics labs.  The real-world phenomena are not nearly as clean and simple as the models put into the simulations (even good simulations like the PhET ones), and learning how to get good measurements and model the data appropriately is the point of doing labs in the first place.  A lot of things that I thought would be simple turned out to have unexpected (by me) complexities. Finding ways to get cleaner data by changing the measurement method or the phenomenon being measured was an important learning experience, as was finding models for the actual observations.  Simulation is good for seeing what a particular model predicts will happen, but comparison to what actually happens is essential.

Reagan chose to explore the “kit” approach further, probably because she also believes that it is the only pedagogically acceptable alternative to the on-site lab (though she is careful not to say so).  She

limited consideration to experiments that 1) were relevant in scope and content to the curriculum of a first-semester introductory physics course, 2) were of appropriate complexity and depth for a college-level course, 3) would provide sufficient accuracy for student analysis and student satisfaction, 4) could be accomplished semi-autonomously by college students in a distance format (e.g., from home, communicating with instructors via e-mail or online chat, only), 5) required direct, hands-on interaction by students with the experimental process, and 6) could be accomplished with inexpensive or readily available materials at a total cost to students for ten such experiments commensurate with the price of a single textbook.

One suggested lab approach that I didn’t use last year, though I would have if I’d thought of it,  is using a microphone and sound software like Audacity for doing timing measurements.  She mentions timing dropped balls and bouncing balls by this approach.  It is probably easier to get clean data for estimating the coefficient of restitution from the times of the bounces than from the long exposure time digital photography method my son used in his fifth grade science fair project, though not as visually appealing. I think that our use of the Arduino for timing (for example, in the speed of sound  lab and the pendulum lab) was at least as effective, and did allow us to use triggers other than sound.

She also talks about using cell phone video cameras, frictionless pucks sold as toys, and Tracker video analysis for some of the other motion labs.  We did not end up doing much video analysis last year, because it was tedious and not well suited to any of the labs we ended up doing.  There were a couple of labs where it might have been a good idea instead of the methods we tried instead.

Interestingly, their first attempt at the Audacity lab for measuring the time for dropped balls was a failure in the real world:

Misunderstandings, misconceptions, and computational errors resulted in student-demonstrated percent errors ranging from 2% to 35%, despite consistent achievement of experimental errors of 1% to 2% in the same experiments carried out by the instructor.

They got much better results when they added video instructions for the labs that addressed common misconceptions and had the students working in a lab where they were observed by an instructor (even though the instructor was not supposed to answer questions). I wonder how much of the improvement resulted from the video instructions and how much from being observed.

 

2012 August 29

Tests for 11th grade

Filed under: home school — gasstationwithoutpumps @ 11:48
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In Home schooling restarts, I listed the courses I thought my son would take this year.  In this post I’ll list the exams I think he’ll need.

test date register by comments
pSAT Oct 17 ? He needs to take pSAT this year for National Merit Scholarships, as he has a good chance of getting one.
SAT Oct 6, Nov 3, Dec 1, Jan 26, May 4, Jun 1 Sep 7, Oct 4, Nov 1, Dec 28, Apr 5, May2 I think that he should take an SAT test early this year, to find out how much more work he needs on SAT essays.  If necessary, he would take the SAT again in the Spring. SAT exams can’t be on the same day as SAT Subject tests, though multiple Subject tests can be the same day.
ACT Oct 27, Dec 8, Feb 9, Apr 13, Jun 8 Sep 21, Nov 2, Jan 11, Mar 8, May 3 ACT is not popular on the coasts, but I’ve heard that some students do better on the ACT than on the SAT (and vice versa).  If his SAT scores aren’t what we hope for, it may be worth doing an ACT test as well.
SAT Spanish with Listening Nov 3 Oct 4 It would probably be better for him to take this text next year, after one more Spanish class.  It is only offered in November.  He could take the SAT Spanish without listening on any other SAT day.
SAT World History Dec 1, Jun 1 Nov 1, May 2 This test may be a way to validate that his idiosyncratic “world history through history of science” covered an adequate amount of world history.  The SAT subject test should be less demanding than an AP test.
SAT Physics May 4, Jun 1 Apr 5, May 2 This test should be pretty easy, compared to the AP Physics C tests, but he’ll need to finish E&M first.  It will help with schools that require two STEM SAT Subject tests.
AP Physics C: Electricity & Magnetism May 14 March? We’ll have to find a school willing to administer this exam, as no high school in the county does Physics C.
AP Computer Science A May 8 March? He may be able to take this at Pacific Collegiate, as they have an AP computer science course.
AP Spanish Language May 8 March? This is scheduled for the same time slot as AP CS, so one of them has to be moved to the makeup slot.
AMC 12 Feb 5, Feb 20 Dec 13 He could take either or both AMC 12 tests this year.  (Taking both increases his chance of being invited to take the AIME test.)
AIME Mar 13?? If he does well on the AMC 12, he could be invited to take the AIME in mid March or early April—it doesn’t seem to have been scheduled yet.

Combining these tests with previous years’ he’ll have 5 AP test scores and 3–4 SAT Subject scores. We’ll have to check the list of colleges he might apply to, to see if any need 5 SAT Subject tests.

Other dates

He has several other scheduled activities this year that need to be planned around.

Activity date comments
Performance Jan 19, 20 Imaginary Invalid at Broadway Playhouse (WEST Ensemble Players)
Performance May 4, 5 The Outsiders at Broadway Playhouse, Saturday morning rehearsal may conflict with SAT. (WEST Ensemble Players)
Performances ? Dinosaur Prom Improv, probably every 6–8 weeks.
Oregon Shakespeare Festival May? Dates for trip not yet on AFE calendar.
County Science Fair Mar 9 If he decides to do science fair this year, he’ll have to register by Feb 15.
California State Science Fair Apr 29–30?? Schedule not posted yet. Only relevant if he decides to do science fair and gets chosen to represent the county at state.
International Science and Engineering Fair May 12–17 Only relevant if he decides to do science fair and gets chosen to represent the county at ISEF. Conflict with AP exams can be resolved by taking exam at ISEF.
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