I spent all day yesterday trying to craft a quiz that would cover all the important topics in the circuits course so far. I feared that it was too long, but I was hoping that students would get half the questions, and that the pattern of errors would show me where students had common misconceptions.
To make the key, my co-instructor, the undergrad tutor, and I each took the quiz ourselves, and I double-checked any answers where we had a discrepancy. I got 29.5/31, my co-instructor got 21/31, and the tutor got 16/31. Their scores tell me that the quiz was too hard (or too time-pressured), as even a professional EE made more than just a couple of arithmetic mistakes. The distribution from the class confirms the problem, with scores ranging from 3/31 to 12/31. I wanted to see a distribution from 10/31 to 25/31.
OK, so I’ve not taught the students some of the things I thought I had taught, and my quiz was both too long and too difficult. Where do I go from here? I can’t fix things right away, as there is one student who was ill and still needs to take the quiz. I’ll probably be able to start correcting the problem on Friday, after this week’s lesson on op amps and the lab.
I can see a few ways forward:
- I could tell them to study and give them another quiz. That would be totally useless, as it would just repeat the problems on this quiz. They don’t know what it is that they need to know, and vague exhortations to study are pointless. I don’t think the problem is lack of effort on their part, and that’s the only problem for which pep talks are a potential solution.
- I could go over the quiz question by question, explaining how I expected students to solve them. This is classic lecture mode and the approach I used to use. It would be easy to do, but I doubt that it would help much. I already did an interactive lecture on the material, and another approach is now needed.
- The students could get the quiz back and be told to go home and look up in their notes and on-line anything they did not get right. They would find and write down the right answers, as if this were homework. (This “quiz correction” is a standard strategy in high school teaching, but not common in college teaching.) One difficulty here is that they might be able to find answers (say by copying from other students in the class) without understanding how to do the problems. It is probably a better approach than yet another lecture, but I’m not sure it will work well enough. If the students were trying to get from 80% understanding to 95%, it might be fine, but to get from 30% to 80%, something more directed is needed. More time and open notes would help, but maybe not enough.
- I could break them into groups and give each group a couple of the problems to work on together in class. This peer instruction technique would be a good one if about 1/2 the students were getting the problems right, but with the top of the class getting only 1/3 right, I may need to give them more guidance than just setting them loose. For example, on some of the problems there was a fundamental misreading of the circuit schematics that was very common. I could clear up that misunderstanding in a minute or so and have them rework the problems that depended on it. Then I could send them home to write correct solutions.
- I could give out lots of problem sets to drill them on the material. Of course, since it took me more than all day Sunday to make an 8-question quiz, it would take me forever to generate enough drill problems to be of any use.
I welcome other suggestions that I may not have considered.
On Wednesday I plan to spend about 20 minutes on inverting and non-inverting amplifiers out of op amps, then 20 minutes on a system block diagram for their audio amp lab, then break them into groups (with whoever their lab partner is for Thursday) to do the audio amp design that they will try to wire up and debug in the lab.
I’ll dedicate Friday’s class to group work on a couple of the quiz problems, with 3 groups of 3–4 students either all groups working on the same problem or each group working on a different problem. I’ll have each group report back to the class as a whole after they’ve solved their problem. This is not a teaching style I’ve used before, and I’m curious to find out whether it will work. Next week I’ll try to get in a gnuplot problem-solving session along the same lines, if I can get the students to bring laptops to class. If these methods work, I’ll try introducing them much earlier next year.
Whatever I do for getting them to master the material, I’ll have to give them another quiz in a couple of weeks to show that they really have mastered it.