Gas station without pumps

2016 February 20

On not using kits for a design class

Filed under: freshman design seminar — gasstationwithoutpumps @ 10:07
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A question came up in e-mail from a student in my freshman design seminar that I had planned to discuss in class, but I ran out of time before getting to it:

Upon determining the actual parts and part numbers for our design, its become increasingly apparent that the DIY kits neatly contain all of the parts we require. Considering this, we wanted to recap with you regarding the DIY kits from our projects. Are we allowed to purchase a kit and build our pulse monitor from it, or are we only allowed to use some parts but not the entire kit?

I answered the student after class, but I wanted to share my thinking more widely.

I like kits in many ways—I learned a lot from building Heathkits as a kid (see Thanks, Dad), but there are limits to what a kit can do for learning, particularly if people just assemble the kit with little or no attempt to understand what each part is for and how the whole thing works.

In a freshman design course, where students know very little or no electronics or programming when they start, the projects that they can reasonably tackle have to be quite simple. Most of the problems that they can solve have been solved before, and solutions by experienced engineers are easily found. Furthermore, commercial solutions are often available for less money than the parts needed to build them, due to the high cost of stocking, distributing, and shipping low-volume parts.

So students who see their role as answer getting are easily convinced to grab one of the good designs so readily available on the Internet and present it as the solution—very little work on their part and a good design, so what could be better?

The problem, of course, is that it is not the goal of the course to have a pulse monitor, an LED cube, or an ultrasonic rangefinder—none of those were part of the syllabus.  I can buy a pulse monitor for a few bucks, and for under $2 an ultrasonic rangefinder module that works better than anything the students are likely to come up. A finished RGB cube is a bit more expensive, but kits are still pretty cheap. One can buy the products the students could produce for far less time and effort than designing and making them. So the product is not the goal of the course.

The goal of the course is for students to (begin to) learn to design things.  This means doing things like writing specifications, drawing schematics, building prototypes, debugging prototypes, writing design reports, and doing iterative prototyping. It means learning a lot about how things work—not everything, but the specific details they need for the projects they have selected. The process of design is the core of the course, not the product of the design.

Buying a kit and assembling it short circuits a lot of that design learning.  You can build a kit and get it working with little or no understanding of how it works, and with no ability to modify the design. Of course, it is not the bundling of parts into a a kit that is the problem—copying a design off the Internet and buying the parts separately also does little to help students learn design. If you just copy other people’s work, then little learning takes place, and there is not much point to doing the class. Perhaps there is a little skill learning—how to use a soldering iron or an oscilloscope and how to order parts from a distributor, but not much how-to-design learning, which is the main point of the course.

That is not to say that students shouldn’t be looking at designs on the web!  Indeed, the freshmen do not have enough of the basic building blocks of electronics and programming to come up with their own designs de novo (though by their senior year they should be able to, if they continue into the bioelectronics or assistive technology: motor concentrations). So they need to look at solutions others have come up with, in order to know where to start on the design. But they should not just pick one design and implement it—they should be looking at several designs and trying to find common elements, figuring out what tradeoffs the different designers have made. Some of the designs come with good explanations of how they work—they should be reading those very carefully, so that they can follow the design decisions and reproduce the design from understanding.

Understanding designs well enough to explain each part, how it functions, and what the effects would be of changing the part may be enough at this stage of their design learning. Part of the point of the freshman design course is to inspire them to want to learn the foundations in other courses, many of which seem to students to be irrelevant gatekeeper classes to survive by cram-and-forget techniques. If they have some idea why complex numbers are important for filter design, or why capacitors are useful, they are more likely to pay attention in those parts of math and physics classes and to retain the knowledge later on.  Of course, it would be best if the math and physics classes included more of the inspiration themselves, but there are many different applications for the material, and it is difficult to find universally inspiring applications—what excites a math major, a computer science major, a physics student, or a bioelectronics student may be quite different, but the same course has to serve all of them.

My role in the classroom is to provide explanations for those things that the students have trouble figuring out on their own, give them generic guidance in the design process, anticipate things they will need to know, and try to hurry them up (in the past most waited far too long before starting their projects, with the result that they get very little done). Having three different projects going on at once means that there is not enough class time for students to get everything they need from me—they must be reading on their own and trying to understand their project thoroughly, but based on the time logs they have been submitting, few in the class have been doing that—they mostly seem to be waiting for me to tell them what to do, which is not going to work for them. I had hoped that having students pick their own projects would inspire them to investigate the projects more deeply without my having to keep kicking them with assignments, but that only seems to be working for a few of the students.

Some aspects of the design they can do—for example, everyone in the class should now be able to size a current-limiting resistor for an LED, and those who need amplifiers should be able to make a simple non-inverting amplifier out of an op amp.  (Hmm, I should probably give a quiz on those ideas next week—maybe the students have absorbed less than I expect.) By this point, the students should be asking about those parts of the design that they don’t understand, but I’m not getting very many questions, despite starting each class asking for questions and covering student-requested material before anything that I have queued up as things students might need.

A big chunk of what the class is trying to do is to nudge students away from regurgitating factoids that have been spoonfed into learning for the sake of understanding deeply enough to do things themselves—that means generating a lot of the questions themselves and seeking solutions by trying things out, and not just by looking up “the answer” or waiting for a teacher to tell them what to do and what to think.  That is a hard transition for many students to make, as they have been steeped in “answer-getting” culture for the past 13 years.


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