Understanding of selected chemical concepts on a submicroscopic level among ninth grade primary school students

V diplomskem delu so predstavljene tri ravni kemijskega pojmaJohnstonov trikotnik treh ravni kemijskega pojmamodel soodvisnosti treh ravni naravoslovnih pojmovmodel poučevanja in učenja kemijevizualizacijska sredstvaPaiviov model dvojne kodne teorijerezultati raziskav, povezanih z razumevanjem izbranih kemijskih pojmov (element, spojina, čista snov, zmes, agregatno stanje snovi, fizikalna sprememba in kemijska reakcija)submikroskopskih predstavitev in simbolnih zapisov enačb kemijskih reakcij ter način poučevanja vseh izbranih kemijskih pojmov, razen čistih snovi na submikroskopski ravni. Glavni namen diplomskega dela je ugotoviti, ali se med učenci devetega razreda osnovne šole pojavljajo težave pri razumevanju izbranih kemijskih pojmov na submikroskopski ravni, prehodov med agregatnimi stanji snovi na makroskopski ravni oziroma kemijske reakcije na simbolni ravni. Rezultati raziskave so pokazali, da imajo učenci devetega razreda največ težav pri prepoznavanju vseh shem, ki ponazarjajo porazdelitev delcev v plinu in pri oblikovanju ustreznega simbolnega zapisa za enačbo kemijske reakcije na osnovi submikroskopske predstavitve. Tudi ugotovitve drugih raziskav kažejo, da imajo učenci težave pri razumevanju simbolnih zapisov. Približno dve tretjini učencev ni razlikovalo med submikroskopskima predstavitvama vode v tekočem in trdnem agregatnem stanju, oziroma ni prepoznalo zmesi elementov, zmesi dveh plinov/zmesi elementa in spojine iz shem porazdelitve delcev. Več kot polovica učencev ni prepoznala prehodov med agregatnimi stanji snovi (vode) na makroskopski ravni (taljenje in izparevanje) ter produkta (plin) in reaktantov kemijske reakcije (2 elementa) iz delčne predstavitve. Manj kot polovica učencev je imela težave pri prepoznavanju fizikalne spremembe in njenih lastnostitekočega agregatnega stanja snovispojine in zmesi plinov iz submikroskopskih predstavitev ter pri razlikovanju med kemijskima pojmoma element in spojina. Devetošolci so bili zelo uspešni pri določanju submikroskopske predstavitve, ki prikazuje element v trdnem agregatnem stanjupri prepoznavanju procesa strjevanja snovi na makroskopski ravni ter zmesi in čistih snovi na delčni ravni. Učenci so bili uspešni tudi pri prepoznavanju procesa kondenzacije na makroskopski ravni in sublimacije na submikroskopski ravni. Ugotovitve raziskave so torej pokazale, da imajo učenci težave pri razumevanju nekaterih izbranih kemijskih pojmov na submikroskopski ravni ter prehodov med agregatnimi stanji vode na makroskopski ravni in kemijske reakcije na simbolni ravni.This diploma thesis discusses the three levels of chemical conceptthe Johnstone\u27s triangle of three learning levels of chemistrythe interdependence of the three levels of science concepts modelthe teaching and learning chemistry modelthe visualization toolsthe Paivio’s dual coding modelthe results of the researches based on understanding of selected chemical concepts (element, compound, pure substance, mixture, state of matter, physical change and chemical reaction), submicroscopic representations, chemical equations and the methods of teaching of all the selected chemical concepts except pure substances on a submicroscopic level. The main purpose of the diploma thesis is to find out whether there are any problems with ninth grade primary school students’ understanding of the selected chemical concepts on a submicroscopic level, the changing states of matter on a macroscopic level and the chemical reaction on a symbolic level. The results of the research have shown that the students in ninth grade have the most problems with decoding diagrams representing the arrangement of particles in a gaseous state and with forming the correct chemical equation on the basis of a submicroscopic representation. Other researches also showed that students have problems with understanding of symbolic forms. Approximately two-thirds of the students did not differentiate between the submicroscopic representations of water in liquid and solid state or did not identify a mixture of elements, a mixture of two gases/a mixture of an element and a compound from diagrams of particle arrangements. More than a half of the students could not identify the changing states of matter (water) on a macroscopic level (melting and evaporation) or did not recognize the product (gas) and the reactants in a chemical reaction (2 elements) based on particulate representation. Less than a half of the students had difficulties with recognizing the physical change and its propertiesthe liquid state of matterthe compoundthe mixture of gases from submicroscopic representations and with differentiating between the chemical concepts element and compound. Ninth grade students were very successful at defining submicroscopic representation of an element in a solid stateat identifying the process of freezing on a macroscopic level and at recognising a mixture and a pure substance on a particle level. They were also successful in identifying the process of condensation on macroscopic level and sublimation on submicroscopic level. The research shows that the students have difficulties with understanding some of the selected chemical concepts on a submicroscopic level as well as the changing states of matter of water on a macroscopic level and a chemical reaction on a symbolic level