Developing labs

We are facing quite a lot of challenges within the field of electronics at our university. In short: there are fewer and fewer students taking electronics courses and we should adapt to that situation.

There would be at least two ways to address the problem: either we scale down or we make the courses more interesting such that, in the end, more students will choose to study electronics. The “problem” however, might be that we are a bit late to offer this change at the university level. Most likely we have to be much more active and visible for children/pupils already in their early teens.

Anyways, while changing courses, why not study one of the perhaps most important elements of the course: the laboratory. This is in some sense the only occasion when the students can practice and try the theory in a context. That sounds easy – doesn’t it? Take a course in basic electrical circuits: It might contain course elements such as DC (Ohm’s law, KCL, KVL) and AC currents (jw, power), as well as something around frequency analysis (amplitude characteristics). Three main parts of the course. Easy as a pie: introduce three laboratories – one on each subject. Happy days. End of story. … Or?

A while ago I visited a seminar hosted by Anna-Karin Carstensen at the Norrköping Campus. A while ago they were intensly studying how the learning process takes place in the laboratory series. They monitored students, filmed them during the laboratory work (asking for permissions of course). Then they analyzed the results. It was for them then quite visible where there were flaws in the laboratories, regardless if theory had been taught in lectures or not. It did not matter if the lecturer thought that all material were there, at the students’ hands. There were simply not the required processes enabling the students to form the links connecting chunks of knowledge/wisdom to to move on in the laboratory series and grasp the knowledge.

It was part of Carstensens Ph.D. studies to monitor these laboratories and develop a method to create a new laboratory where students should more easily link between pieces of knowledge to understand the “whole” picture.

Yes, I know that nomenclature fails me, I am not trained in this field of research. I am trying to give my review in a straight-forward approach.

Consider the picture below, which at a first glance might look a bit simple. It depicts the learning processes, the links, in a laboratory, where the aim is to sort of “understand the Laplace transform”. How do you make the connection between time domain, frequency domain, poles and zeros, and the Laplace transform. The task of the lab is to curve-fit and find important parameters of the step response of an RLC circuit (resistor, inductor, capacitor). By doing this, a better understanding for how the location of poles and zeros, i.e., coefficients in the Laplace polynomial, affect the step response, should be developed.

This picture is from Carstensen’s dissertation and I have got the permission to publish it here..

Now, the point is to sit down and actually look at the laboratory and its manual. What pieces of the puzzle do we have at hand? How will the students see these pieces? You want the students to bridge all links (verbs btw, actions), such that they move around freely and “understand”, “conceive”, in the graph above.

Let us start in the top left corner of the circle (you know what I mean…). Students are given a real circuit, including a schematic (at this stage of their training, they conceive the schematic as a “real circuit”). From that you derive the differential equation. From there on, through replacing operators with s or 1/s, you get to Mr. Laplace. Or you would get to Laplace from the real circuit by doing some KCL&KVL exercises and replacing C with 1/sC, etc. Through tables you would get from Laplace to the time-domain representation, you would be plotting it and you would be comparing it with the measured graph. The graph is measured on our real circuit. And we are back at stage one. That sounds pretty straight-forward right?

Well, yes, perhaps. But actually, you want the student to understand, not just walk around the circle and applying a standard set of rules. You want them to do the connections and not a) get stuck in smaller loops and not b) run the outer loop. They must be able to get from any point to any other. Those links, or enablers for them, must be in the lab too, otherwise it is just a fill-in-the-blank-boxes exercise.

Much more can be said, I just wanted to inspire to do some more reading at before you plan your next lab and I will try to adapt this way of thinking for next year’s TSTE92 Electrical Circuits.


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