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This study examined how teachers teaching chemistry at different levels of education perceive their levels of technological pedagogical content knowledge (TPACK) and examined the relationship of TPACK with age, gender, teaching at different levels of education, time spent teaching chemistry, and frequency of information and communication technology (ICT) use. The study involved 261 teachers, 246 women and 15 men, from all over Slovenia, who have been teaching chemistry for an average of 18 years at different levels of education, with an average age of 45 years. The results showed that teachers teaching chemistry content perceive a high level of TPACK. There is a statistically significant correlation between age, time spent teaching chemistry, and frequency of ICT use with the perceived level of technological pedagogical content knowledge. Younger teachers, those with less professional experience and teachers who use ICT more frequently rated their TPACK higher. Based on the results of the survey, guidelines for planning the in-service teacher training that would support the development of TPACK of teachers teaching chemistry content were developed.

The paper presents a study in which 54 university students were introduced to a newly developed, free, web-based 3DChemMol molecular editor with a toolbar, which they then evaluated. The tool aims to increase representational competence related to submicroscopic representations. Students who used the software for the first time, were instructed to create molecular models using the model building/editing tools in three activities with varying levels of difficulty: 1) building a simple model (butanoic acid), 2) converting one model (hexane) into two models, 3) converting from a non-cyclic to a cyclic structure (glucose). It took students from two up to 15 minutes to accomplish each of the activities. Several types of help were available in the 3DChemMol molecular editor toolbar to assist students during their activities, including a video tutorial, button hovering, action status display, and a help menu. Undo/redo and restart options were also available. Students' completion level, difficulties, and use of the help features were investigated using student self-evaluation questionnaires. The 3DChemMol molecular editor proved to be a useful support for students in completing simple chemistry activities. Students were successful in model building, although they encountered some specific difficulties, especially in steps that involved spatial operations, such as rotating the selected part of molecule around the bond. In students' perception, the video tutorials were the preferred and most frequently used type of help, and the undo function was considered essential. The results suggest that the 3DChemMol molecular editor can be used effectively in introductory chemistry courses at the tertiary level, whether for direct instruction, self-study, or other forms of support in the pedagogical process. The results and new findings of this study will be used to further optimize the interface in future versions of the evaluated tool.

The aim of the research was to optimize the effectiveness of student learning based on experimental work in chemistry classes in Slovenian primary schools. To obtain evidence about how experimental work is implemented during regular chemistry classes, experimental work was videotaped during 19 units of chemistry lessons at 12 Slovenian primary schools from the pool of randomly selected schools. Altogether 332 eight-grade students were involved in the investigation, with an average age of 14.2 years. Students were videotaped during chemistry lessons, and their worksheets were collected afterward. The 12 chemistry teachers, who conducted lessons in these schools, were interviewed before the lessons; their teaching plans were also collected. The collected data was analyzed using qualitative methods. The results indicate that many teachers in Slovenian primary schools are not fully aware of the potential of experimental work integrated into chemistry lessons for the development of students' experimental competence. Further research of the value of different kinds of training to support teachers for the use of experimental work in chemistry teaching is needed.

The research presented in this article deals with the self-evaluation of 4th year pre-service chemistry teachers' progress during their second year practical pedagogical training in chemistry teaching at primary schools (students' age 13-15 years) in comparison to the perception of their progress by their school mentors. The sample consisted of 21 pre-service teachers and 21 school mentors, in-service chemistry teachers, at primary schools. For the purpose of following to pre-service chemistry teachers' development, the pre-service teachers as well as their mentors completed the "Questionnaire for monitoring students' progress", focusing on eight characteristics of professional development during practical pedagogical training. The results reveal that student-teachers were stricter in their self-evaluation in comparison to their school mentors after their first chemistry lecture at school during the practical pedagogical training; however, after their last lecture, the evaluations were similar for most of the characteristics. The development of five randomly selected student-teachers is presented in detail from their own perspectives, as well as from their school mentors' perspectives.

When learning chemistry, students encounter various visualizations introducing scientific concepts and processes unobservable to the naked eye. It is often assumed that these visualizations support students' understanding and enable them to solve problems more efficiently. The research presented here investigates students' use of an explanatory key while solving tasks based on submicroscopic representations. The following features of the explanatory key were examined: 1) colored versus black-and-white, and 2) pictorial versus textual. Eye-fixation patterns and students' verbal explanations indicated that the presence of color in the key does not influence students' task solving. However, significant differences were observed with regard to a textual versus pictorial key used in the tasks: students spent more time and fixated more frequently on the key while solving tasks using a textual key in comparison to a pictorial key. The results indicate that the type of explanatory key might play an important role in revealing students' representational competence with regard to submicroscopic representations.

Science educators have suggested many benefits that accrue from engaging students in experimental activities, therefore, experimental work has a long and distinctive role in chemistry curriculum since. The presented empirical study focuses on the valuation of effectiveness of different forms of experimental work - students' hands-on experimental work vs teacher's lecture demonstration - from the viewpoint of the quality of content knowledge acquisition and knowledge retention in teaching primary school chemistry. 106 primary school students (age 14-15 years) participated in the study. The data was collected via pre- and post- test protocol and two delayed post tests. Additionally 16 students selected from the sample were interviewed. The results indicate that students' content knowledge gained through teacher's demonstration of experiment is better and better knowledge retention takes place in comparison to students' knowledge gained through students' hands-on experimental work. However, most of the inteviewed students stated that they prefered conducting of experiments by themselves in comparison to observation of teacher's demonstration.

Paraffinic phase change materials (PCM) were microencapsulated by in situ polymerization of melamine-formaldehyde prepolymers. Partly methylated trimethylolmelamine was used as an aminoaldehyde prepolymer for the microcapsule wall, a styrene-maleic acid anhydride copolymer as an emulsifier and modifying agent, and ammonia as a scavenger for reducing residual formaldehyde. For the determination of residual formaldehyde in a ppm concentration range, EDANA and malachite green analytical methods were studied, and the EDANA 210.1-99 was applied for the determination of residual formaldehyde in 25 samples of microcapsules, produced in a 200-L reactor. A linear correlation was observed between the added ammonia scavenger concentration and the reduction of residual formaldehyde concentration. Compared with 0.45% (4500 ppm) formaldehyde in a non-treated microcapsule suspension, with ammonia scavenger concentrations 0.80, 0.90 and 1.35%, the concentration of residual formaldehyde dropped to 0.27, 0.20 and 0.09% (i.e. 2700, 2000 and 900 ppm), respectively. Morphological characterisation of microcapsules by SEM and microcapsule wall permeability measurements by gravimetry / mass loss at an elevated temperature (135 °C) suggested that ammonia positively contributed to the wall elasticity / durability, while microcapsules with no ammonia scavenger added tended to have more brittle walls, and were more prone to cracking.