Research in Engineering Education Symposium 2011 - rees2009

Universidad Politécnica de Madrid (UPM) Página 48 de 957
the question that was asked. However, this in itself is an interesting result as these
students seemed to be lacking an understanding that the methods of circuit analysis they
had studied were based on certain assumptions and that the degree to which these
assumptions are satisfied by real-world objects could be tested empirically.
Examination question: The second of the two quiz questions was also given as part of the
final examination to a different cohort of the same course (TUHH-ME). Tasks (a) and (b)
were reversed in order, i.e. the question about voltage was asked first. To simplify the
grading process, the question was given in a pure multiple-choice format; no explanation
of student reasoning was asked for.
When given as part of the examination, the three tasks yielded results that were quite
similar to those obtained in the ungraded quiz. The task about the voltage across bulb A
(now in first place) was answered correctly by 52% of the students (versus 50% on the
quiz); that about the current through the same bulb by 90% (versus 82%). The
percentages of students giving a correct or partly correct answer to task (c) were again
very similar, with 26% correctly choosing only statement Y and an additional 10%
choosing statements X and Y (versus 23% and 14%), as a fraction of those answering (a)
and (b) correctly in both instances.
We take the results of the examination question to confirm the results of the quiz question
shown above. From a methodological point of view, this indicates (in agreement with prior
experience) that even ungraded quizzes can yield reliable data on student knowledge and
understanding. The slight increase of student success on the most straightforward of the
questions asked (90% versus 82% correct answers about currents in series) may likely be
due to the effect of studying for final exams. Both results consistently show, however, that
questions about the assumptions of the linear circuit model, especially those that involve
reasoning with observed or given experimental data, remain very difficult for the students.
Conclusions
While all the questions administered to the students as part of an ungraded quiz or
examination were considered “fair game” by the respective instructors, we are aware of
the fact that both types of the questions shown here are non-standard. Apart from a brief
interlude in one lecture during which various modeling aspects were introduced, this topic
was not discussed in the course. We may then conclude that if as instructors of circuit
analysis we want students to gain a functional understanding of the course content as a
mathematical model for real-world circuits, the relationship between these two “worlds”
has to be made explicit. It is in this sense that we agree with some of the conclusions put
forward a few years ago by Carstensen and Bernhard (2007). Our results not only indicate
that many students do not understand or do not appreciate the “model” nature of the
linear circuit model in electrical engineering. On the basis of the results of our first
question above, we also believe that this lack of understanding or appreciation actually
hampers their performance on more traditional tasks in circuit analysis, especially those
that require a functional understanding of electric potential.
Proceedings of Research in Engineering Education Symposium 2011
Madrid, 4 th - 7 th October 2011