Comparative study of student understanding of some basic concepts in mechanics and electromagnetism

Maja Planinić



            The results of  physics education research, that come from studies carried out in many countries worldwide, have shown that students' understanding of basic concepts in physics is often inadequate. Students' alternative conceptions seem to play a major role, since they often interfere with the development of students' conceptual understanding in physics.

            In Croatia, large scale research of students'  understanding of basic concepts in mechanics and electromagnetism is still missing. This dissertation presents and links the results of three studies that involved the total of about 800 Croatian high school and university students. The aim was to analyze the prevalence of alternative conceptions in mechanics and electromagnetism, and the influence of those conceptions on  students' conceptual understanding in each domain.

            Three tests have been used in the study: one designed by the author, which probed students' alternative conceptions regarding Newton's laws and simple DC circuits, and two American tests,  Force Concept Inventory (FCI), and Conceptual Survey in Electricity and Magnetism (CSEM). The first study involved not only the analysis of students' responses, but also the analysis of students' confidence levels that accompanied those responses. It was possible to identify students' firm alternative conceptions through students' incorrect answers accompanied by high levels of confidence. The data was analyzed with the stochastic Rasch model, that enabled the transformation of raw measurement results into linear measures. The second study compared difficulties of six conceptual areas in CSEM. The results of Croatian students were compared with the published results of a large number of American students. In the third study, the FCI and CSEM results of several groups of Croatian students were compared.

            The test results show that Croatian students' understanding of basic concepts in the two investigated domains of physics is mostly inadequate, but also suggest that the role of alternative conceptions is not completely the same in mechanics and electromagnetism. The strongest students' alternative conceptions were found in mechanics. They sometimes persist even until advanced levels of physics learning and might present the biggest problem for the development of students' conceptual understanding in mechanics.  The results of the FCI test have shown that only a small fraction of Croatian students (only 10% in a sample of high school graduates) are above the Newtonian threshold, which is defined as 60% on FCI. It has also been demonstrated that mechanics - related alternative conceptions cause conceptual problems in electromagnetism.

            In electromagnetism, most alternative conceptions were linked to electric circuits, but  students' low confidence in their answers suggested that alternative conceptions in this area may not be as strong as those in mechanics. In other parts of electromagnetism alternative conceptions mostly originated from students' tendencies to simplify complex abstract concepts or to reduce them to simpler concepts. Through comparison of difficulties of six conceptual areas in CSEM it was established that the most difficult area is the electromagnetic induction, the second difficult areas being Newton's laws in electromagnetic context, and the electric potential. The same order of difficulties of conceptual areas was found for American students. It seems that in electromagnetism the main problems for students are highly abstract concepts, their graphical representations (e.g. field lines, equipotential lines) and the lack of firm conceptual models.

            It is suggested that interactive teaching methods could help in resolving students' conceptual difficulties in both domains of physics.