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Namen predstavljene raziskave je bil izboljšati učinkovitost učenja ob uporabi eksperimentalnega dela pri pouku kemije v slovenskih osnovnih šolah. Preučevali smo, kako se eksperimentalno delo izvaja pri rednem pouku kemije, in sicer je bilo posnetih 19 učnih enot rednega pouka kemije na 12 slovenskih osnovnih šolah, ki so bile naključno izbrane iz seznama šol iz celotne države. Skupno je bilo vključenih 332 osmošolcev, s povprečno starostjo 14,2 let. Učenci so bili posneti med poukom kemije, zbrani pa so bili tudi njihovi delovni listi, ki so jih reševali med eksperimentalnim delom. Z učitelji kemije, ki so izvedli pouk v teh šolah, so bili opravljeni intervjuji, prav tako so bili zbrane njihove učne priprave. Pridobljeni podatki so bili analizirani z uporabo kvalitativnih metod. Rezultati kažejo, da se mnogi učitelji v slovenskih osnovnih šolah v celoti ne zavedajo potenciala eksperimentalnega dela pri poučevanju kemije. Potrebne so nadaljne študije, s katerimi bo preučena vrednost različnih oblik izobraževanja v podporo učiteljem pri nadaljnem razvoju na področju uporabe eksperimentalnega dela pri pouku kemije. 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.

V članku predstavljena raziskava se ukvarja s samo-evalvacijo napredka med praktičnim pedagoških usposabljanjem bodočih učiteljev kemije, študentov četrtega letnika, v primerjavi z mnenjem njihovih mentorjev na šoli. Vzorec sestavlja 21 bodočih učiteljev kemije in 21 njihovih mentorjev, izkušenih učiteljev kemije na osnovnih šolah. Za namen spremljanja razvoja bodočih učiteljev kemije med praktičnim pedagoških usposabljanjem so bodoči učitelji in njihovi mentorji izpolnjevali »Vprašalnik za spremljanje razvoja bodočih učiteljev kemije«, ki temelji na evalvaciji osmih karakteristik strokovnega razvoja učiteljev kemije. Rezultati kažejo, da so bili bodoči učitelji kemije v samo-evalvaciji bolj strogi od svojih mentorjev, še posebno po prvi izvedeni uri pouka kemije, medtem ko so bile ocene po zadnji izvedeni uri podobne z ocenami mentorjev glede večine ocenjevanih karakteristik. Podrobneje je predstavljen razvoj petih naključ no izbranih bodočih učiteljev kemije iz njihovega osebnega vidika, kakor tudi iz perspektive njihovih mentorjev. 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.

Densities of ethanol-water mixtures have been measured using a vibrating tube densimeter and a different arrangement high-pressure experimental set-up. Measurements were carried out at 298,15 K in a pressure range from 0.1 MPa to 5MPa. Partial molar volumes, excess molar volumes and coefficients of isothermal compressibility were calculated. The molar volumes of alcohol and its partial molar volumes in mixtures with water are found to decrease monotonously with increasing pressure. Excess molar volumes are negative at all pressures. The numerical P-V relations at each composition are correlated satisfactorily as a function of pressure by the Hayward equation. Gostote mešanic etanola z vodo smo izmerili z gostometrom, ki je bil prirejen za visokotlačne poskuse. Meritve so potekale pri 298,15 K v območju tlakov od 0,1 MPa do 5 MPa. Iz izmerjenih gostot smo izračunali parcialne molske prostornine, presežene molske prostornine in koeficiente izometrične stisljivosti. Molske prostornine etanola in njegove parcialne molske prostornine v mešanicah z vodo se monotono zmanjšujejo s povečanjem tlaka. Pri vseh tlakih so presežene molske prostornine negativne. Numerične P-V zveze v odvisnosti od tlaka so za vsako sestavo raztopine podane s Hayworthovo enačbo.

Recent investigations have shown that modification of polymer matrix with filler and elastomers significantly affects composite's mechanical properties. Isotactic PP modified with either untreated or treated talc and either SEBS or SEBS-gMA were used in these investigations. Samples were prepared by melt-mixing in a Brabender kneading chamber and were compression molded into plates on a laboratory press. The composites were characterised by measuring mechanical properties (Young's modulus, yield stress, notched impact strength) and by defining morphology. Binary sistems PP/talc and PP/elastomer containing up to 16 vol.% of talc and up to 10 vol.% of elastomer, as well as ternary PP/talc/elastomer composites with 12 vol.% talc were investigated. Ternary composite's yield stress was also calculated by semiempirical equations. We have found out, that the use of treated modifiers (talc or elastomer) improves adhesion with matrix, which reflects on mechanical properties as better stress transfer. Novejše raziskave so pokazale, da lahko z modifikacijo polimerne matrike s polnilom in elastomerno fazo znatno vplivamo na mehanske lastnosti nastalega kompozita. V raziskavah smo uporabili izotaktični PP ter ga modificirali z neobdelanim oz. obdelanim talkom in SEBS oz. SEBS-gMA. Vzorce smo pripravili preko taline v Brabenderjevem gnetilniku in s stiskanjem v plošče na laboratorijski stiskalnici. Karakterizirali smo jih z merjenjem mehanskih lastnosti (Youngov modul, meja plastičnosti, zarezna udarna žilavost) in z opredelitvijo morfologije. Preučevali smo binarne sisteme PP/talk in PP/elastomer z vsebnostjo talka do 16 vol.% in do 10 vol.% elastomera, kakor tudi ternarne kompozite PP/talk/elastomer z 12 vol.% talka. Mejo plastičnosti ternarnih kompozitov smo določili še s polempiričnimi enačbami. Ugotovili smo, da uporaba obdelanih modifikatorjev (talka oz. elastomera) izboljša adhezijo z matriko, kar odseva na mehanskih lastnostih kot boljši prenos napetosti.