The aim of the research was to identify how Slovenian primary and secondary school students of various age groups explain the particulate nature of the states of matter of water and air. The qualitative research included five 12, 14, and 16 year old students. A semi-structured interview including four computer-displayed tasks was used for the data collection. The research results show that all of the students correctly identified the states of matter of water at the particulate level, but not of air. It was found that the students had difficulty justifying their selection. The study confirmed the existence of: (a) misunderstanding regarding the interpretation of the particulate nature of matter, (b) a failure to distinguish between particle and matter, and (c) the inadequate description of submicroscopic level of matter with macroscopic level concept. The survey results provide an insight into the mindset of students and serve as a starting point for teachers’ lesson planning. Keywords: authentic tasks, macroscopic level, misunderstanding of pressure, states of matter, submicroscopic level.

The purpose of this paper is to explore and explain students’ achievements in solving context-based gas exercises comprising the macroscopic and submicroscopic levels of chemical concepts. The influence of specific variables, such as interest in learning, formal-reasoning abilities, and visualisation abilities, is a significant factor that should be considered when explaining students’ achievements with context-based exercises. Seventy-nine students of three age groups (12, 16, and 23) participated in the study. Questionnaires, tests, and a semi-structured interview including computer-displayed context-based exercises were used to collect data. In addition, an eye-tracker was used to determine the exact location of the participants’ points of gaze. The results show that students on average answered correctly from 40 to 79% of all questions in the context-based exercises. The context-based exercise related to air compression is indicated as being difficult for students. In students’ explanations of different levels of chemical concepts, representation difficulties are detected in all three age groups of students. Students’ achievements in solving context-based gas exercises do not depend on interest in learning chemistry and visualisation abilities. However, statistically significant differences exist in total fixation duration on the correct submicrorepresentation animation between students with different formal-reasoning abilities. The results serve as a starting point for the planning of different context-based exercises and problems comprising the chemistry triplet with 3D dynamic submicrorepresentations.

This paper aims to identify differences in the justification of the selection of 3D dynamic submicroscopic-representation (SMR) of the solid and liquid states of water, as well as the freezing of water presented in selected authentic tasks. According to students' achievements in solving these tasks at different levels of education, their explanations were identified. To explain in greater detail how students attempted to solve the authentic tasks, an eye-tracking method was used to identify the differences in the total fixation durations on specific areas of interest at the specific SMRs between successful and unsuccessful students in three age groups. A total of 79 students participated in this research. The data were collected with a structured interview conducted with students when solving three authentic tasks displayed on the computer screen. The tasks comprise text (as problem and questions), macro-images (photos of the phenomena) and SMRs of the phenomena. The eye-tracker was also used to measure the students' gaze fixations at the particular area of interest. The results show that successful students' justifications for a correct SMR include macroscopic and sub-microscopic representations of the chosen concepts. Along different stages of education, the selection success increases and sufficient justifications comprise the sub-microscopic level. It could be concluded that there are mostly no significant differences between successful and unsuccessful students within the same age group in the total fixation duration at the correct SMR. Further studies are needed to investigate the information-processing strategies between high and low achievers in solving various authentic tasks comprising SMRs and those that integrate all three levels of the representation of chemical concepts.

Learning and presenting chemical concepts at the triple level of chemical concepts provides opportunities for the development of misconceptions. The research aimed to identify potential misconceptions of chemical concepts: the states of matter, a pure substance, a mixture, an element, a compound, a physical change, and a chemical reaction at the sub-micro level when solving problems incorporating sub-microrepresentations. A total of 188 14-year old students, attending six different primary schools, participated in the research. A chemistry achievement test comprising five problems at the macroscopic, sub-micro, and symbolic levels was used to obtain data about students' misconceptions of selected concepts. The results showed that the majority of students had formed inadequate mental models (misconceptions) for the chemical concept of the liquid state of water (66.5%). The lowest level of misconceptions is related with the gaseous state of matter, because almost all students (98.5%) solved the problem correctly. It can be concluded that the results of the research are significant for chemistry teachers because they can: select and apply adequate educational strategies to avoid the deepening or development of misconceptions and make the courses practically oriented by analysing students’ misconceptions and develop teaching strategies to minimise these problems in the chemistry classroom. Keywords: chemical concepts, primary school, misconceptions, sub-micro level, symbolic level.

The main purpose of this study was to identify understanding of atmospheric pollution phenomena such as acid rain, global warming, ozone layer depletion and photochemical smog among grade 9 lower secondary school students (aged 14 to15), in all Slovenian regions. The research involves the development of a three-tier multiple-choice diagnostic test entitled the Atmospheric Pollution Phenomena Diagnostic Test (APPDiT). APPDiT is a 15-item diagnostic test comprising items for assessing students' understanding and self-confidence of atmospheric pollution problems. The results reveal that the majority of the participants demonstrated a lack of knowledge or misconception about atmosphere pollution since the overall success rate on the APPDiT was 39.6%. In particular, only 36.7%, 5.1%, 42.7% or 19.1% of the students have adequate knowledge regarding understanding of the formation, consequences, and strategies to reduce acid rain, global warming, ozone layer depletion and photochemical smog, respectively. This shows a substantial students' knowledge deficits related to atmosphere pollution at the end of the compulsory education in Slovenia.