Analysis of Engineering Students’ Common difficulties with DC electric circuits in an Inquiry-based laboratory

The students’ understanding about direct current electric circuits’ concepts has been extensively investigated in secondary schools as well as at university level. In the University of São Paulo (IFSC/USP), for more than 10 years, our group has been researching the Electricity and Magnetism laboratory course to Engineering students’. Similarly to reported in the literature, we observed that students often leave physics classes with less of an understanding of physics concepts than we had expected. In this paper we present an investigation of the difficulties that students in the Electricity and Magnetism laboratory have with current electric circuits' concepts and how that research was used as a guide in the development and evaluation of the guided-inquiry lab on these topics to help students learn these concepts better. Initially, we adapted a question developed by McDermott in 2006 and employed it to investigate students’ conceptual understanding of electric circuits in three states of Brazil. STEM areas were involved in this research and the question was applied after students attended to theoretical and laboratory courses. Students had to order light bulbs according to brightness in three different electric circuits to answer the question. Only ~13% of students answered correctly agree to result in other countries and it inspired us to restructure the laboratory guide from a course in our institution. Our new guide was inquiry-based with some activities adapted from Tutorials in Introductory Physics and others developed in a prediction-observation-explanation form. The same question was used as pre and post-test and the average percentage of students who got the maximum score was 47%. We also have been using the Determining and Interpreting Resistive Electric Circuit Concepts Test (DIRECT), which is composed by a 29-multiple choice questions, that can be grouped in conceptual objectives, allowing us identifying specific conceptual difficulties. We proposed many modifications in the students’ guide, after analyzing the questions, and some of them we managed to improve, like those related to resistance and current. On the other hand, less than 50% of students could answer correctly some questions related to the concepts of power and voltage in the post-test, even after our efforts to improve learning in this aspect. We have been able to help students overcome known conceptual difficulties with the proposal of new activities, but some difficulties still a challenge to be outgrown. This fact has shown us that research for improving practice is fundamental to overcome persisting difficulties and is a long-term and constant action. Also, using different resources such as homework activities on the internet, videos and computer simulations have shown to be useful tools as supplement materials.