Category Archives: Flipped Classroom

The Tinkering Thinker

Recently, I helped to give two workshops at Universidad del Turabo in Puerto Rico on the use of personal instrumentation (e.g. Digilent’s Analog Discovery, National Instruments myDAQ and their version of Analog Discovery 2, Analog Devices ADALM 1000 …) in the teaching of circuits and electronics. In attendance were great people from all of the engineering schools on the island. They were really engaged and asked wonderful questions, even though several were uncomfortable working exclusively in English.

One of the best questions I was asked has helped me to formulate what is, I hope, a very productive way of framing the discussion of how best to educate engineers. I was trying to make the case for Experiment Centric Pedagogy (ECP), for which the guiding hypothesis is that students and instructors are more motivated and engaged and engineering education works best in a learning environment where experimentation plays a central role. This is in contrast to  the traditional STEM classroom: the lecture hall, occasionally augmented with separate labs provided as expensive limited access facilities permit.

Engineers must tinker with ideas but, unfortunately, modern technology is so complex that tinkering has generally become too difficult. (There is an excellent article on the early days of the Mobile Studio Project in the Sept 24, 2007 issue of EETimes on this topic.) Those of us old enough to have developed our interests in electronics and electrical phenomena in the 1950’s were lucky enough to work mostly with discrete components (tubes!) which allowed for a lot of tinkering and shocks and burns.

The question raised at the Turabo workshop had to do with Thinking vs Tinkering. Traditional, lecture-based instruction requires students and instructors to think their way through a subject and the questioner was concerned that student tinkering may just be a trial and error effort to find an approach that involves little or no thinking. I certainly agree that I have, for example, seen students randomly make a bunch of attempts with a spreadsheet to solve a problem without really learning what they did and why it worked. The best scenario is that they know how to repeat what they did in the same way that the work their way through a video game. However, in spite of what often happens, tinkering and thinking are not exclusive activities.

Let’s look at tinkering a little differently and ask the following questions: Can we get a tinkerer to think or can we get a thinker to tinker and which is better? That is, should our students be Thinking Tinkerers or Tinkering Thinkers? From the title of this posting, it should be obvious what I think. It is also what nearly everyone I know says (so far anyway) when I ask them to choose. Whether or not we recognize that we are asking our students to apply the scientific method, we all work hard to get our students to predict what is going to happen (hypothesis) before they do an experiment (testing). Again, what we see too often is students cranking through a task list without stopping to think about what they are doing and why. That is why thinking comes first and we have the Tinkering Thinker.

Voltage Divider Circuit (Wikipedia) & Breadboard Version (Electroschematics.com) 

An example of ECP: One of the most ubiquitous and useful circuits is the voltage divider, which I will use to show an example of ECP in action. The goal of ECP is to think our way through the process of understanding how a particular circuit works by tinkering with it both experimentally and using simulation. The process could be shown as a flow chart, but I would rather keep it more informal than that.

  1. What is a voltage divider? Look it up on Wikipedia or in a textbook. The former approach seems like the most common these days. It is also very often possible to find good videos on topics like this. I have done a bunch on the voltage divider … more on that at the end of this example.
    1. From available information, find the circuit Diagram and what it looks like when it is built? The two figures above show examples of each.
    2. What is the formula that characterizes its operation? A common question because the first thing needed is how is it analyzed or how do we use it?  In the Wikipedia, the relationship between the output and input voltages is given as  V_\mathrm{out} = \frac{R_2}{R_1+R_2} \cdot V_\mathrm{in}
  2. Build one and see what it does? Before doing any analysis, build one and try it.
    1. It has to be built correctly and data collected correctly, so some basic experimental skills are necessary. Build the circuit … connect the sinusoidal voltage source (aka function generator) … measure accurately both the input and output voltages. It is almost always necessary to measure both.
    2. How do measurements compare with the ideal formula? Are there any data features that do not agree with formula? Is the formula general enough? What happens when we add a load? What happens if it works well with 1kΩ resistors but not if it is made with 1MΩ resistors?
  3. Simulations do not show noise unless it is specifically added. Simulations are usually more ideal than experiments. Simulate it to see if there are any things left out in the ideal formula? This can be done with any version of the SPICE program. LT-Spice from Linear Systems, is a good choice because it is free.
    1. When this is done, it is seen that the simple divider seems OK. Maybe this verifies that simulation is being done properly in addition to showing us what the voltage divider does in an ideal world.
    2. Voltage dividers have no purpose unless we connect something to them to read the output voltage. Does adding a load affect its operation? It should be observed that loading does make the divider work differently, just as it did experimentally, except without the noise.
  4. Go back to the basic reference used and see how the formula is derived. What are the assumptions? Are any violated with loading?
    1. Basic analysis is based on Ohm’s Law and that the current in both resistors is the same (the resistors are in series). This is clearly not the case with a load, but, if the load resistance is 100 times R2, it will have no noticeable impact on the operation of the circuit.
    2. Analysis with load — eureka! Since adding the load resistor does not really make the analysis much more difficult (R2 is replaced by the parallel combination of R2 and the load resistor), a new formula can be derived that does a very good job of predicting the output voltage.
  5. Go back to the experiment and look at non-ideal characteristics that occur with different resistances, voltage levels, frequency, etc. Determine the limits for application of the ideal model. This and the preceding steps are addressed in a series of videos I made for my Electronic Instrumentation class. Watch the first three videos for the topics addressed here: https://www.youtube.com/playlist?list=PLZXERmYWSLA9n_ar9LJGUrSJRAUDMpzuu 
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Goodbye, Podium: an Engineering Course Puts Theory Into Practice

The following was originally published 1 October 2012 in the Chronicle of Higher Ed.

I don’t do lectures anymore. Not in the usual sense. And I’ve never had so much fun teaching.

If I get an idea at home for my electronics-instrumentation class, I plug my Mobile Studio IOBoard—a small, inexpensive circuit board that allows students to do multiple electronics tasks without a lot of bulky equipment—into my laptop. I then build a circuit activity, record a lecture, add a paper-and-pencil exercise and an appropriate computer model, and I’m all done. I don’t have to wait until I get to the campus and find an open time in my lab. I can even ask a TA or a former student or a colleague at another university for feedback. The students can carry out their experiments anywhere, I can do my work anywhere, and I can get help from anyone because we all have the same set of simple, mobile learning tools.

Students get the same lectures I would give in person, but the focus is on doing things with the information rather than sitting passively and watching someone else demonstrate. When we meet for a two-hour session, they’ve already listened to the lecture, sketched out a circuit diagram, done some calculations. They’re ready to build and test a circuit at their desks, or may have done part of the activity at home. The recorded lectures become one more tool for the students to consult to help them through the experiments. One of my friends who teaches at a university in Utah won’t let students into her electromagnetic-theory class until they prove they’ve watched the lecture; they also have to bring proof that they’ve done the reading and some kind of homework.

The whole point is to use the class time well.

When students complete a lab experiment at home or in a staffed lab on campus, they come to class better able to explain what they’ve done and why they think the approach is correct, and to provide explanations or questions about any problems they encountered.

What is so cool is that the learning experience has all the key aspects of the complete engineering-design cycle—no matter where the students do the work. The combination of traditional paper-and-pencil calculations, simulation, and experimentation leading to a practical system model makes it possible for them to think and act much more like practicing engineers.

Here at Rensselaer Polytechnic Institute, we call this hands-on approach the Mobile Studio Project (mobilestudioproject.com). The concept grew out of some fantastic but hideously expensive studio classrooms (about $10,000 per seat) that RPI built in the 1990s to bring multiple engineering activities into one well-outfitted room. Each station had a full set of lab equipment, a desktop computer, and tables for taking lecture notes and doing hand calculations. There was a natural progression from introducing a topic and advancing to paper and pencil, simulation, and experiments, with breaks for group and one-on-one discussions. Maybe there was an hour of lecture or maybe 10 minutes, but after that the class would try something. More often than not, the class began with a demonstration or a hands-on activity. You’d build, you’d talk.

It was so much fun. I just loved it. We thought we’d ushered in a new way of teaching. But very few engineering schools adopted this model because it was so expensive and the studio classrooms held just 30 to 40 people. Our enrollments went up, and we had more students than we knew what to do with. The model simply was not scalable, even for us.

With the advent of laptops, we realized we didn’t need a special studio room. We could do all the activities except those that required access to lab equipment. We just had to figure out a way to add that capability to the students’ laptops. We tried a variety of existing options, mostly involving some kind of inexpensive data-acquisition board, but either they did not have the functionality we needed or they were much too expensive. And then we discovered we were at one of those magical crossroads where it became possible to imagine that every engineering student could be given his or her own personal mobile electronics laboratory.

What happened? A combination of better and cheaper electronics, strong leadership, and financial support from the National Science Foundation and industry led Rensselaer—with help from Howard University and the Rose-Hulman Institute of Technology—to develop the Mobile Studio.

The latest version of the Mobile Studio hardware costs about $150 per student—cheap enough that every engineering student gets his or her own board. (For information on acquiring the hardware, visit the project’s Web site.) So now we can take a studio approach in any decent classroom. More important, when students learn with Mobile Studio, their homework and test scores go up and learning improves, as documented by the University at Albany Evaluation Consortium, which provides independent assessment of research and pedagogy.

The most exciting results come from synthesis questions in which students are required, for example, to design a circuit with a specific functionality. Students who work with the Mobile Studio have significantly higher scores than those who do not.

Students can pursue their own ideas, build something, and then try it either just for their own satisfaction or, in my class, for more points. This style of teaching closely resembles the way engineers do their jobs and allows the students to achieve understanding based on what they do best.

Once students could do labs at home, the new technology suddenly opened up dimensions we hadn’t thought of before. Courses that never had lab experiments have them now. For example, mechanical- and civil-engineering majors learn circuits through minilabs that might last 20 minutes. Students can now be asked to do homework involving hardware. They can also tinker at their own projects.

As I said, if I get an idea at home, I just set up my Mobile Studio, build the circuit, and see what happens. I don’t have to wait for the classroom. This is the direction in which engineering education is going. New modes of delivery made possible by an ever increasing array of products will make the present way we teach unrecognizable. I might never need to stand behind a podium again.