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This research aimed at evaluating pre-service science teachers’ understanding of the subject matters such as “thermochemistry, chemical kinetics, chemical equilibrium, acids and bases and electrochemistry”. For this purpose, a two-tier diagnostic test consisting of 44 items (α = 0.84) related to the aforementioned concepts was developed by the researchers. This test was applied on to the first, second, and third year pre-service science teachers in Hasan Ali Yucel Education Faculty, Istanbul University. The results showed that the pre-service science teachers had alternative conceptions about endothermic-exothermic reactions, conservation of energy, reaction enthalpy, calorimeters; rate of reaction, reaction rate constant, effects of some factors on reaction rate and reaction rate constant; effects of some factors on equilibrium, equilibrium dynamics, Le Chatelier Principle; equivalence point, end point, indicators, buffers, titrations, neutralization, strength and properties of acids and bases, pH; effects of concentrations on cell potential, metal electrodes, localization of anode and cathode, plating, galvanization. Key words: acids and bases, alternative conception, chemical equilibrium, chemical kinetic, electrochemistry, thermochemistry, two tier diagnostic test.

This study was conducted to investigate the effects of laboratory activities based on predictobserve-explain tasks related to the subjects of "Mixtures, Physical and Chemical Changes, Acids and Bases" on pre-service elementary teachers' understanding and attitude toward chemistry lesson and chemistry laboratory. For this purpose, the pre-service elementary teachers were randomly assigned to experimental (N=26) and control (N=30) groups. The experimental group was instructed using laboratory activities based on predict-observe-explain task and the control group was taught using traditional cook-book design laboratory activities during ten weeks. For the data collection, a two-tier concept test, attitude toward chemistry lesson scale and attitude toward chemistry laboratory scale were applied before and after the instructions. The results indicated that the pre-service elementary teachers who were trained using laboratory activities based on predictobserve-explain task had significantly higher scores in terms of achievement and attitude toward chemistry lesson and laboratory than those taught by the traditional approach. It was also found that instruction for laboratory activities based on predict-observe-explain task was more successful in remediation of the predetermined alternative conceptions. Sakarya University Journal of Education 185çekleştirilirken, kontrol grubu geleneksel yaklaşıma dayalı yürütülmüştür. Veri toplama aracı olarak iki aşamalı kavram testi, kimya dersine karşı tutum ölçeği ve kimya laboratuvarına karşı tutum ölçeği kullanılmıştır. Sonuçlar tahmin gözlem açıklamaya dayalı laboratuvar etkinlikleri yapan sı-nıf öğretmeni adaylarının geleneksel yaklaşıma dayalı etkinlikler gerçekleştirenlere kıyasla başarı, kimya dersine ve kimya laboratuvarına karşı tutum açısında istatistiksel olarak anlamlı düzeyde daha yüksek puana sahip olduklarını göstermiştir. Ayrıca tahmin gözlem açıklamaya dayalı laboratuvar etkinliklerinin çalışmanın öncesinde belirlenen alternative kavramları gidermede oldukça başarılı olduğu bulunmuştur.Anahtar Kelimeler: Asitler ve bazlar, fiziksel ve kimyasal değişim, kavramsal anlama, karışımlar, kimya dersine ve kimya laboratuvarına karşı tutum ölçeği, tahmin-gözlem-açıklama.

Abstract. This study aimed to investigate the impact of virtual chemistry laboratory instruction on pre-service science teachers' scientific process skills. For this purpose, eight laboratory activities related to chemical kinetic, chemical equilibrium, thermochemistry, acids-bases, and electrochemistry were developed. Those activities were performed in virtual laboratory environment by the pre-service teachers in the experimental group and in the real laboratory environment by c the preservice teachers in the control group during eight weeks. Scientific process skills test developed by Burns, Okey and Wise [3], and translated into Turkish by Ateş and Bahar [2] was used before and after the instructions for data collection. According to results, while there was no significant difference between pre-test mean scores (U=133.500, p>0.05), significant difference between post-test mean scores was found in favour of experimental group (U=76.000, p<0.05). In addition, while no significant difference between pre-test mean scores for each sub-dimension was found, significant difference between post-test mean scores for designing investigation and formulating hypothesis skills was found in favour of experimental group.