In this work we describe the development of the kinetic molecular theory of liquids (KMTL) concept inventory, as well as its use in investigating students’ conceptual understanding of the KMTL within the contexts of aggregate states, evaporation, boiling, condensation, conduction, convection, diffusion, and surface tension. We implemented think-alouds to prepare distractors for the closed-ended version of the KMTL, which was administered to two groups of respondents: non-physicists and physicists (166 students in total from the Universities of Rijeka and Split, Croatia). From the think-alouds and results of written survey research we drew conclusions about the students’ understanding of the structure of matter, thermal internal energy, entropy, temperature, and pressure. Our study not only reiterates earlier findings on students’ ideas about the KMTL, it also reveals numerous additional misconceptions that had not been reported earlier. Psychometric analyses support a formative use of the KMTL inventory. The inventory questions may be extensively used for identifying misconceptions, as well as for stimulating classroom discussions and conceptual change.

Research has shown that students have tremendous difficulties developing a qualitative understanding of wave optics, at all educational levels. In this study, we investigate how three different approaches to visualizing light waves affect students’ understanding of wave optics. In the first, the conventional, approach light waves are represented by sinusoidal curves. The second teaching approach includes representing light waves by a series of static images, showing the oscillating electric field vectors at characteristic, subsequent instants of time. Within the third approach phasors are used for visualizing light waves. A total of N=85 secondary school students were randomly assigned to one of the three teaching approaches, each of which lasted a period of four class hours. Students who learned with phasors and students who learned from the series of static images outperformed the students learning according to the conventional approach, i.e., they showed a much better understanding of basic wave optics, as measured by a conceptual survey administered to the students one week after the treatment. Our results suggest that visualizing light waves with phasors or oscillating electric field vectors is a promising approach to developing a deeper understanding of wave optics for students enrolled in conceptual level physics courses. (IPN/Orig.)

In this study we investigated how two different approaches to drawing free body diagrams influence the development of students' understanding of Newton's laws including their ability to identify real forces. For this purpose we developed a 12- item two-tier multiple choice survey and conducted a quasi-experiment. This experiment included two groups of first-year physics students from Rijeka (RG) and Split (SG) University. Students from both groups solved mechanics problems for a period of two class hours. The only difference was that RG students used the superposition of forces approach to solving mechanics problems and in SG the decomposition of forces approach has been used. The ANCOVA showed a statistically significant difference in favour of RG, whereby the effect sizes were moderate to large, and largest differences have been observed in the ability of identifying real forces. Students from the control group (SG) more often exhibited the misconception that forces and their components act on a body independently and simultaneously. Our results support the idea that the practice of resolving forces into components may not be the most effective way to develop understanding of Newton's laws and the concept of force.