J. Brás Barreto de Oliveira

São Paulo State University - UNESP (BRAZIL)
The low learning in Physics and Mathematics topics, in the early grades, represent a barrier to the further development of students in science, technology, engineering and math (STEM) courses, causing problems such as increased dropout rate. In Brazil this derivate from significant gap between the level of learning at the end of secondary school and that required at University.

One of the serious difficulties in Physics is the approach of classical electromagnetic theory, which requires ability to abstract. Studies have pointed the main conceptual difficulties and suggested procedures to address them, many using active teaching methods.

In this paper we investigate the impact of the inverted classroom methodology and of the active and collaborative engagement of students on the learning of concepts related to the Gauss`s Law, one of the four Maxwell`s equations, in which the flow of electric field through a closed surface called Gaussian is related to electrical charge inside the Gaussian. The calculation of the flow requires the solution of an integral surface, a nontrivial visualization step.

Specifically, the difficulties of the students lies in establishing the association between the distribution of electrical charges in space and the electric field lines configuration and, also, how to choose the appropriate Gaussian in order to explore the possible symmetry of the electric field.

In this work were studied two groups of 30 students enrolled in basic electricity and magnetism subjects. For the first group, the definition of Gauss's Law and its applications had addressed through traditional lectures based on widely used textbooks. In the second group, students carried out previous activities answering guiding conceptual issues; they were encouraged to read texts and access videos on the topic. In the class, in five student subgroups, using different and simple materials, they set up a physical representation of the electrical carrier distribution, the respective field lines and the selected Gaussian´s surface and applied the mathematical equation. Both groups (N=30) worked with spherical, cylindrical and planar carrier distributions and the time devoted to classroom activities was about the same.

A post-test with five multiple-choice questions was applied to both groups, in the same conditions, and the performance compared. Additionally, the success of students in the conceptual post-test were compared to they own performance on the exam for admission to University and on the performance in two disciplines of Physics and two of Mathematics concluded before.

The results showed that:
a) the number of correct answers was higher for students in the second group (active methods), and
b) students of the second group (active methods), with relatively low previous income, compared with students of first group (traditional lectures), were more successful in the applied post-test.

Although the data are preliminary and require further data and analysis it indicate that the active engagement student before and during the class and the "materialization" of carrier distribution, of the field lines and of Gaussian surfaces contributed to improve the conceptual understanding students on this fundamental topic.

[1] Justyna P. Zwolak and Corinne A. Manogue, Assessing student reasoning in upper-division electricity and magnetism at Oregon State University, Phys. Rev. Special Topics – Physics Education Research 11, 020125 (2015)