Examining Strategies Used by Pre-service Science Teachers in Stoichiometry Problems in Terms of Proportional Reasoning

Yıl 2019, Cilt: 48 Sayı: 1, 910 - 944, 21.04.2019

Tezcan Kartal Büşra Kartal

Öz

Stoichiometry problems are one of the best examples
of problem solving in chemistry education. Proportional reasoning supports
correct answers in stoichiometry problems. It is needed to examine how these
problems are solved as well as the accuracy of solutions because of the
importance and benefits of conceptual problem solving. This study utilizes the
embedded multiple case study design. The stoichiometry problem solutions of 37
pre-service science teachers (PSTs) were examined based on three units of
analysis; (i) whether pre-service teachers balanced the equations correctly or
not, (ii) the accuracy of solutions, and (iii) strategies used to solve
problems. More than half of the PSTs balanced the equations correctly but most
of them did not interpret the integers in the equations appropriately.
Participants were inclined to use algorithmic approach more than proportional
reasoning. The accuracy of solutions and the frequency of algorithmic approach
increased while the complexity of problems decreased. PSTs had difficulties in
making sense of integers of chemical reactions, using intensive units such as
density, and converting units. It is thought that PSTs prefer to use strategies
that they learnt in their prior learning experiences. Within the context of
findings, we suggest that PSTs should be supported conceptually about the
meanings of integers and should be introduced using proportional reasoning in
problem solving prior to algorithms.

Anahtar Kelimeler

Stoichiometry problems, proportional reasoning, pre-service science teachers

Fen Bilimleri Öğretmen Adaylarının Stokiyometri Problemlerinin Çözümünde Kullandıkları Stratejilerin Orantısal Akıl Yürütme Açısından İncelenmesi

Öz

Orantısal akıl yürütmenin doğru sonuca ulaşmayı
sağladığı stokiyometri problemleri kimya eğitiminde problem çözmenin en iyi
örneklerinden biridir. Kavramsal problem çözmenin önemi ve faydaları göz önüne
alınarak, stokiyometri problemlerine ilişkin çözümlerin doğruluğunun yanı sıra
nasıl bir yaklaşımla çözüldüğünün de incelenmesi gerekmektedir. Bu amaçla
araştırmada nitel araştırma yöntemlerinden bütüncül çoklu durum kullanılmıştır.
Çalışmada, 37 fen bilgisi öğretmen adayının stokiyometri problemlerine ilişkin
çözümleri (i) tepkimeleri doğru denkleştirilip denkleştirilmediği, (ii)
çözümlerin doğruluğu ve (iii) problem çözümünde kullanılan stratejiler olmak
üzere üç adımda incelenmiştir. Öğretmen adaylarının yarısından fazlasının tepkimeleri
doğru denkleştirdiği ancak denkleştirilmiş tepkimelerdeki katsayıları doğru
yorumlayamadığı görülmüştür. Öğretmen adayları algoritmik yaklaşımı orantısal
muhakeme stratejilerinden daha fazla kullanmayı tercih etmiştir.  Soruların karmaşıklık düzeyi arttıkça
öğretmen adaylarının problemleri doğru çözme ve algoritmik yaklaşımı kullanma
oranları azalmıştır. Öğretmen adaylarının stokiyometri problemlerini çözerken tepkimelerdeki
katsayıların belirttiği molar oranı tam olarak anlamlandıramadığı, tepkimeye
giren maddelerden biri yoğunluk gibi intensif bir birim cinsinden verildiğinde
çözüme ulaşamadıkları ve birimleri doğru dönüştüremedikleri gözlemlenmiştir.
Öğretmen adayları stokiyometri problemlerini daha önceki derslerinde nasıl
çözmeyi öğrenmiş iseler yine aynı şekilde çözmeyi tercih ettikleri
düşünülmektedir. Bulgular çerçevesinde, kimyasal tepkime problemlerinden önce
katsayıların ne anlama geldiği ile ilgili kavramsal desteğin sağlanması,
problem çözümüne orantısal akıl yürütme stratejileri ile başlanarak bu desteğin
işlemsel süreç ile pekiştirilmesi önerilmiştir.

Anahtar Kelimeler

Stokiyometri problemleri, orantısal akıl yürütme, fen bilimleri öğretmen adayları

Kaynakça

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