The determination of Pb and Cu with a Nafion-modified glassy carbon electrode and MnCo 2 O 4 nanoparticles as working electrode for anodic stripping voltammetry was described. Pb and Cu were accumulated in HCl/KCl (0.1 mol/dm 3 ) at a potential of -1.4 V (vs. Ag/AgCl electrode) for 480 s followed by a linear sweep anodic stripping voltammetry (ASV) scan from -1.0 to +0.5 V.Under optimum conditions the calibration curves were linear in the range of 0.01 -8 mg/dm 3 and 0.01 -5 mg/dm 3 for Pb and Cu, respectively. Effect of sample dilution, accumulation time and potential were optimised. A study of interfering substances was performed. A significant increase in current was obtained at modified electrode in comparison with bare glassy carbon electrode. The modified electrode was successfully applied for determination of Pb and Cu in wine samples after simple preparation procedure. Pb and Cu content in wine was used for estimation of the target hazard quotient (THQ) values for minimal and maximal levels of the metals.

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the course of this research, we explored the extent of chemistry teachers? professional knowledge related to the structure, contents and application of chemistry curricula and their components. The research comprised 119 teachers from 69 secondary schools (25 grammar schools and 44 vocational secondary schools). The questions in the questionnaire referred to general curriculum knowledge, knowledge of chemistry curriculum and the views/assessments of teachers concerning the necessary changes in the curricula currently in effect. The teachers? answers show that the most important components of the curriculum for their work are the goals and operative tasks/outcomes. The results indicate that there exists information in the curriculum components that remains unused although it is relevant for a certain level of planning. Among the teachers in the sample, higher percentages of those with appropriate teachers training programme were applying information from the curriculum within teaching process through demonstration method and problem solving. The research that was conducted provides a basis for defining the indicators for monitoring the level of teachers? capability to apply curricular knowledge in their practice. Such indicators are important for creating teaching situations and teachers? activities within the framework of initial teacher education and continuing professional development. [Projekat Ministarstva nauke Republike Srbije, br. 179048: Scientific Theory and Practice in Society: Multidisciplinary, Educational and Inter-generational Perspectives]

The flipped classroom model has been increasingly implemented in the teaching and learning process at all levels with a view to improving the teaching and learning process, particularly in the present circumstances. Despite the prevalence of the view that the implementation of this approach eliminates the key disadvantages of traditional teaching such as the passivization of students, it is advisable to verify this in practice. In order to examine the effectiveness of the implementation of the flipped classroom model, it is necessary to consider the results of students' learning and their motivation for learning relative to the traditional instruction model. This paper aims to provide insight into the current situation through the systematization of the results of some past research focusing on comparing the implementation of the flipped classroom model and the traditional instruction model in terms of their effects on internal motivation for learning and student achievement on knowledge assessment tests. The results of the conducted meta-analysis of 22 research papers suggest that the implementation of the flipped classroom contributes to the strengthening of students' internal motivation and their higher achievement.

One of the main reasons for low achievement of our students in international tests is the lack of functional, applicable knowledge. Formation of such knowledge demands changing the usual way of implementation of instruction (transfer of ready-made knowledge) to learning through performing simple research and practical work. Considering the fact that instruction, as an organised process, takes place in frameworks determined in advance, which are arranged and regulated on the national level by curricula, it is assumed that this kind of approach must originate precisely from curricula, which is not the case in our educational practice. The goal of this paper was to determine the way in which this kind of approach in instruction and learning of chemistry can be supported by the curriculum, in order for it to become a part of regular teaching practice on the national level. The paper presents how different structural components of curricula from eight different educational systems (four European countries, one Asian country, two American federal states and one Canadian province) are used to promote and support the importance of research work in instruction and learning of chemistry. The curricula from Slovenia, England, Denmark, Malta, Singapore, North Carolina, Utah and Ontario were analyzed in order to determine the kind of information they offer within structural components and accordingly, the way in which each component promotes research approach to learning chemistry, how it guides the teacher in planning such activities in the classroom, organization and performing instruction, monitoring and evaluating students' achievements