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.

Many physics curricula are opened with the study of kinematics, because such practice is considered to be a logically grounded way for introducing the students with fundamental concepts and methods of pyhsics. Consequently, the approach to teaching kinematics significantly influences not only the students' knowledge of kinematics, but also their learning of other areas of physics, as well as their attitudes towards physics instruction, in general. It is theoretically supposed that understanding of kinematics can be fostered by providing the students with external visualizations, as well as with the opportunity to take measurements of physical quantities. In our study, we aimed to compare the impact of simulations, sequences of simulation frames and conventional static diagrams on students' learning performance in one-dimensional kinematics. Our student sample consisted of three classes of middle years students (N=63 ; mostly 15 year olds). Each of these classes has been assigned to one of the experimental treatments, whereby the treatment variable reflected the use of the abovementioned media types. In order to answer our research question, we conducted a pre- post quasi- experiment with three comparison groups. The results of the ANCOVA showed that students who learned from simulations or from printed sequences of simulation frames significantly outperformed their peers who learned one-dimensional kinematics from conventional static diagrams. Thereby, the results of our study indicate that learning from sequences of simulation frames seems to be particularly productive for girls. Finally, the data from our attitude survey suggest that students are very motivated for learning from simulations or sequences of simulation frames and they consider them as a very useful tool that considerably helped them to learn the difficult kinematical concepts.

Received 11 March 2014; accepted 21 April 2014We investigated students’ understanding of satellite motion around the Earth. For that purpose, we surveyed high-school and universitystudents from Croatia. With the objective of gaining insight into teachers’ understanding of students’ abilities, physics teachers were asked topredict students’ answers. The results of the study suggest that most students have difficulties with providing physically based explanations.They tend to approach such problems through the use of phenomenological primitives. Specifically, they tend to use the “closer is stronger”p-prim when attempting to identify the satellite orbit which would ensure receiving satellite television signal at a certain location paying noattention to the direction of the gravitational force. We found no statistically significant association between the students’ ability to correctlyexplain the satellite motion and their educational background. The teachers considerably overestimate students’ abilities. Generally, theresults of this study suggest that diagram-based problem can be useful tool for probing students’ understanding of satellite motion.Keywords: Diagrammatic representation; satellite motion; students’ problem solving.Hemos investigado el entendimiento de los estudiantes del movimiento del sat´elite alrededor de la Tierra. Con este fin hemos hecho un estudiode los estudiantes de la secundaria y los estudiantes universitarios de Croacia. Con el objetivo de comprender la habilidad de los ense˜nantesde entender las habilidades estudiantiles, les hemos pedido a los profesores de f´isica prever las respuestas estudiantiles. Los resultados de lainvestigaci´on sugieren que la mayor ´ia de los estudiantes tiene dificultades a la hora de dar explicaciones f ´isicamente fundamentadas. Ellostienen la tendencia de abordar estos problemas usando los conceptos fenomenologicamente primitivos. En concreto, tienen la tendencia de´usar “p-prim closer is stronger” cuando tratan de identificar la orbita de un sat´ elite que deber´ ´ia asegurar la recepcion de se´ nal de televisi˜ on´por sat´elite en cierto lugar, sin tener en cuenta la direcci on de la fuerza gravitacional. No hemos encontrado una relaci´ ´on estad ´isticamentesignificativa entre las habilidades estudiantiles de explicar correctamente el movimiento del sat ´elite y su formaci ´on. Los ense nantes estiman˜mucho m´as de lo que valen las habilidades estudiantiles. En general, los resultados de esta investigaci on sugieren que los problemas con los´diagramas pueden ser una herramienta util para investigar el entendimiento estudiantil del movimiento del sat´ elite.´Descriptores: Representacion diagram´ ´atica; movimiento del sat elite; solucionamiento estudiantil del problema.´PACS: 01.40.Fk; 01.40.gb; 01.55.+b

When solving physics problems, students often fail to identify real forces acting on the body under consideration [1]. This problem is mainly due to the abstract nature of the force concept, but it can also result from the traditional teaching methods. Typically, the mathematical approach to physics problem solving is characterized by introducing additional, nonexistent forces, thus leading to a loss of physical clarity. Vector calculus, in most physics courses, is carried out by the traditional algebraic methods, i.e. by resolving the forces into components and then summing up the components of the same direction. In this procedure the number of the vectors appearing in the force diagram is significantly increased. Although this procedure facilitates the calculation, it potentially leads to the misconception that the components are also some real forces. In addition, the procedure is not entirely in accord with the concepts of the Newton’s laws which state that the motion of the body is determined by the vector sum of the forces, usually not considering the components. The question arises: is the direct vector method [2] or application of the polygon rule for vector addition more successful in teaching mechanics? In this study, we have developed an instrument that aims to measure the extent to which students can identify the real forces in different diagrams. Unlike the FCI test, which mainly checks for preconceived notions, our test checks for didactogenic misconceptions. In addition, our multiple choice questionnaire is based on the visual representation, where the students have to choose the diagram that correctly presents only the real forces. Using this instrument we made an initial study of the effectiveness of the two different problem solving methods. Our test, consisting of 12 items, was administered to the two groups of first-year physics students at Rijeka (RG) (n = 27) and Split (SG) (n = 25) University, after the “concept of force” had been covered in class. We found the pretest item difficulty index ranging from 0.12 to 0.83, with the discrimination values from 0.21 to 0.93 and the KR-20 reliability estimate 0.72. Afterwards, both groups exercised additional force diagrams tasks for a period of two class hours. The only difference was that RG used the polygon rule and SG the vector components method. Posttest showed a shift in the average rate of correct responses which was larger for RG. The normalized average gain in RG was 0.46 compared with 0.24 in the SG. The ANCOVA showed a statistically significant difference (p=0.009) in favor of RG. Based on these initial results we formulate the working hypothesis for the future investigation: If we apply the teaching method where the force diagrams are solved, not by separating force vectors into the components, but by adding them by using the polygon rule, we foster students' ability to identify real forces and we improve their understanding of Newton's laws. Further tests of this hypothesis are the subject of our future work. References [1] For a recent review of literature see e.g. A. Savinainen et al., Phys. Rev. ST Phys. Educ. Res. 9, 010104 (2013). [2] A.S. Kondratyev, W. Sperrym, Phys. Teach. 32, 417 (1994).

This work is aimed at exploring some pedagogical opportunities of using photographs in physics instruction. In our study, the photography has been used for eliciting and probing students’ ideas regarding the physics of fluids in noninertial frames of reference and under conditions of equilibrium. The study involved a heterogeneous sample of 235 secondary school students, 41 physics students, and 48 physics teachers. They were presented with a photograph of a wine glass filled with liquid whose surface appeared inclined. The students were asked to comment on the reality of the phenomenon captured in the photograph, and the teachers were asked to predict the students’ responses. The results showed that about half of the students had a complete or partially complete understanding of the physical ideas and that their practical and conceptual knowledge was not dependent on their education level or curriculum followed. Most of the respondents found the task interesting and relevant. The results indicate that th...

In this Reply to the Letter to the Editor, it is emphasized that scientific inquiry requires a cyclic interplay of quantitative and qualitative methods. Furthermore, it is stressed out that the results of the predominantly quantitative study could be a basis for designing detailed qualitative studies of country-specific cultures of physics education. The overlooked fact that students from Slovenia were not taught about two topics related to ‘Electricity and magnetism’, did not compromise the results of differential item functioning/differential group functioning procedures, at all. The big majority of conclusions related to causes of students' differential achievement profiles were not affected either.

Hemos investigado las habilidades estudiantiles de revisar la definicion de un problema fisico y la significatividad de la solucion. La muestra constaba de 276 estudiantes de secundaria y universitarios croatas. Los estudiantes, que estaban en niveles diferentes de educacion, estaban familiarizados con los conceptos fisicos correspondientes. Los procesos del pensamiento critico de estudiantes eran investigados basandose en su respuesta a dos problemas mal definidos abiertos. Tambien era investigada la habilidad de profesores de prever el enfoque estudiantil tipico. Para esta ocasion 48 profesores respondieron a una encuesta de tipo cerrado compuesta de respuestas verdaderas de los estudiantes a dos problemas mal definidos. Los resultados muestran que los problemas mal definidos pretenden estimular a los estudiantes a expresar una gama amplia de sus ideas muy arraigadas sobre la significatividad del planteamiento y la solucion del problema. Los resultados indican tambien el nivel bajo del pensamiento critico estudiantil, independientemente del nivel de educacion y del curriculo. La enserianza tradicional obviamente no desarrolla suficientemente el pensamiento critico. Los profesores estiman correctamente la habilidad estudiantil de revisar la realidad del resultado, pero por otra parte, sobrestiman considerablemente su criticismo a la hora de definir el problema. Creemos que este tipo de problemas podrian facilitar el esfuerzo de profesores dirigido hacia el desarrollo sistematico de los procesos del pensamiento critico estudiantil. Por consiguiente, el afrontamiento de estudiantes a los problemas mal definidos podria ayudarles en mejorar sus competencias en la vida real, tanto como desarrollar la costumbre de tomar una postura critica hacia la definicion y la solucion de problemas fisicos

In international large-scale assessments of educational outcomes, student achievement is often represented by unidimensional constructs. This approach allows for drawing general conclusions about country rankings with respect to the given achievement measure, but it typically does not provide specific diagnostic information which is necessary for systematic comparisons and improvements of educational systems. Useful information could be obtained by exploring the differences in national profiles of student achievement between low-achieving and high-achieving countries. In this study, we aimed to identify the relative weaknesses and strengths of eighth graders’ physics achievement in Bosnia and Herzegovina in comparison to the achievement of their peers from Slovenia. For this purpose, we ran a secondary analysis of Trends in International Mathematics and Science Study (TIMSS) 2007 data. The student sample consisted of 4,220 students from Bosnia and Herzegovina and 4,043 students from Slovenia. After analysing the cognitive demands of TIMSS 2007 physics items, the correspondent differential item functioning (DIF)/differential group functioning contrasts were estimated. Approximately 40% of items exhibited large DIF contrasts, indicating significant differences between cultures of physics education in Bosnia and Herzegovina and Slovenia. The relative strength of students from Bosnia and Herzegovina showed to be mainly associated with the topic area ‘Electricity and magnetism’. Classes of items which required the knowledge of experimental method, counterintuitive thinking, proportional reasoning and/or the use of complex knowledge structures proved to be differentially easier for students from Slovenia. In the light of the presented results, the common practice of ranking countries with respect to universally established cognitive categories seems to be potentially misleading.

For the purposes of tailoring physics instruction in accordance with the needs and abilities of the students it is useful to explore the knowledge structure of students of different ability levels. In order to precisely differentiate the successive, characteristic states of student achievement it is necessary to use test items which possess appropriate discriminatory behavior. By identifying the cognitive factors which account for differences or similarities between high achievers and low achievers, we can evaluate the efficacy of developing various aspects of physics competence within the physics instruction. Further, knowing the predictors of physics item discrimination power makes it possible to systematically modify physics items with the purpose of improving their psychometric characteristics. In this study, we conducted a secondary analysis of the data that came from two large-scale assessments of student physics achievement at the end of compulsory education in Bosnia and Herzegovina. Foremost, we performed a content analysis of 123 physics items that were included within abovementioned assessments. Thereafter, an item database was created. Items were mainly described by variables which were supposed to reflect some basic cognitive domain characteristics of high and low achievers. For each of the items, we calculated the item discrimination power. Finally, a regression model of physics item discrimination power was created. It has been shown that 43,6 % of item discrimination power variance can be explained by factors which reflect the automaticity, complexity and modality of the knowledge structure that is relevant for generating the most probable correct solution, as well as by the constructs of cognitive load and retention. Interference effects between intuitive and formal physics knowledge structures proved to influence the item discrimination power, too.

Large-scale assessments of student achievement in physics are often approached with an intention to discriminate students based on the attained level of their physics competencies. Therefore, for purposes of test design, it is important that items display an acceptable discriminatory behavior. To that end, it is recommended to avoid extraordinary difficult and very easy items. Knowing the factors that influence physics item difficulty makes it possible to model the item difficulty even before the first pilot study is conducted. Thus, by identifying predictors of physics item difficulty, we can improve the test-design process. Furthermore, we get additional qualitative feedback regarding the basic aspects of student cognitive achievement in physics that are directly responsible for the obtained, quantitative test results. In this study, we conducted a secondary analysis of data that came from two large-scale assessments of student physics achievement at the end of compulsory education in Bosnia and Herzegovina. Foremost, we explored the concept of ``physics competence'' and performed a content analysis of 123 physics items that were included within the above-mentioned assessments. Thereafter, an item database was created. Items were described by variables which reflect some basic cognitive aspects of physics competence. For each of the assessments, Rasch item difficulties were calculated in separate analyses. In order to make the item difficulties from different assessments comparable, a virtual test equating procedure had to be implemented. Finally, a regression model of physics item difficulty was created. It has been shown that 61.2% of item difficulty variance can be explained by factors which reflect the automaticity, complexity, and modality of the knowledge structure that is relevant for generating the most probable correct solution, as well as by the divergence of required thinking and interference effects between intuitive and formal physics knowledge structures. Identified predictors point out the fundamental cognitive dimensions of student physics achievement at the end of compulsory education in Bosnia and Herzegovina, whose level of development influenced the test results within the conducted assessments.