Life without chemistry is difficult to imagine in today's world. Chemistry enables understanding and research of numerous natural phenomena and the emergence of new consumer goods which are part of everyday life. Chemistry at primary school is one of the most challenging natural sciences because it includes many new and abstract scientific concepts which students find difficult to conceive and comprehend. The key to better understanding of the complex chemistry contents is to appreciate the triple nature of the concepts in order to present chemistry notions and concepts on the macroscopic, sub-microscopic, and symbolic levels. Students gravitate to the macroscopic level the most because they can perceive certain chemistry notions and concepts with their visual, auditory, olfactory, and tactile senses. The most abstract and uninteresting aspect of chemistry for them is the symbolic domain where the macroscopic observations have to be translated into suitable symbols, formulas, or equations. The sub-microscopic level is a part of the abstract domain as well because the macroscopic observations are explained at the level of particles (atom, molecule, ion). However, for a complete understanding of chemistry it does not suffice to offer an explanation based just on one of the domains identified. All three domains must be equally integrated into the process of teaching and the study of chemistry notions and concepts. Schools use sub-micropresentations (SMR) which show analogue models of a particular chemical element or substance to illustrate these notions and concepts in the domain of particulates. The SMR presentations are the key factor in studying and understanding the chemistry syllabus for students at all levels of education because they stimulate in-depth learning. Incorrect or inconsistent use of the triple nature of chemical concepts can lead to misconceptions and deficient knowledge of the chemistry syllabus. Good instruction needs to consider student's previous knowledge, his or her mental ability and the complexity of the transition between the macroscopic, sub-microscopic, and symbolic domains. Other factors, which should not be ignored, are a student's motivation, his or her attitude towards chemistry and interest in studying the triple nature of the chemistry concepts. These factors influence the concepts of learning and affect the student's success in solving the tasks in a particular context.
The results of this master thesis show the following: (1) the domains where students have more difficulties in reading or drawing the SMR of chemical reactions; (2) the most common misconceptions which occur in drawing chemical reactions at the sub-microscopic level; (3) how a student's attitude towards chemistry affects his or her success in solving chemical reaction tasks at the level of particulates; and (4) whether the use of sub-micropresentations in chemistry lessons influences the success in solving chemistry tasks. The survey was conducted at six primary schools in different areas of Slovenia. It included 250 primary school students who were finishing the 9th grade of primary school in 2017/2018 and their chemistry teachers. The results of the survey are systematically presented in several topical sets. The results show that Slovenian primary school students have more difficulties in drawing the SMR of a chemical reactions than in reading them because they do not follow the relevant rules and laws of chemistry. Students experience the major share of difficulties in considering the size of the particles they have to draw, determining the aggregate state of metals, metal oxides, and aqueous solutions of salts. Students also find it difficult to consider the stoichiometric relationship between the individual elements of reactants and products. In addition, this research effort reveals that recognizing diatomic molecules poses another problem for students. They would draw the hydrogen and oxygen gases in the form of atoms. Another difficult issue is the naming and writing of a symbol and a molecule formula. The results of the thesis show that students with a greater individual interest in studying chemistry are more successful in solving the tasks, which are based on reading and drawing the SMR of chemical reactions. The level of students' success is affected by the use of sub-micropresentations in chemistry lessons. The students whose teachers often include schematics of particulates in their chemistry lessons are more successful in solving such tasks. The data collected reveals that a teacher's way of a lesson planning results in his or her teaching style and the students' understanding of chemistry reactions at the level of particulates. If a teacher frequently discusses chemistry concepts at each of the three concept domains and prepares tasks, which reinforce and revise the learning of the content, the students understand the chemistry syllabus better and misconceptions are less likely to develop.
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