Effects of Teaching Based on Cognitive Conflict about Thin Film Interference on Students’ Conceptual Understanding
Journal Name:
- Amasya Üniversitesi Eğitim Fakültesi Dergisi
Keywords (Original Language):
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Abstract (2. Language):
Problem Statement: It is evident that studies conducted on the physics topics of heat and temperature, electric current, Newton‟s laws of motion and force are numerous in the literature. However, the number of studies corcerning thin film interference in the wave model of light unit in physics is sparse in the literature. It is wondered to what extent teaching based on a conceptual change strategy is effective in learning of thin film interference which is both an abstract notion and has a low possibility of being held an idea about itself beforehand. It is therefore whether the thin film interference teaching based on conflict between ideas, which is one of the conceptual change strategies, is effective on conceptual understandings of students forms the problem of this study. Purpose of the Study: Purpose of this study is to examine the effect of conceptual change strategy based teaching on grade 11 students‟ conceptual understandings about thin film interference which is the subtopic of wave model of light unit.
Method(s): Mixed method research in which qualitative and quantitative research methods are used together is preferred in this study due to desire to examine the effects of teaching based on conflict between ideas within one of the conceptual change strategies in detail (Tashakkori ve Teddlie, 1998; Creswell ve Plano Clark, 2007). While qualitative data were collected by considering the qualitative research design, quantitative data were gathered to support the qualitative data that formed sequential mixed model design. In this study, readiness test, conceptual understanding test and semi-structured interviews were used as primary data collection instruments. Additionally, students‟ notebooks were inspected and diaries were checked during the teaching period. Worksheets were handed out throughout teaching and observation data were collected by recording presentations and interactions within the class. Sample of the study is comprised of 41 students attended two classes of grade 11 level at an Anatolian high school at the county of Edremit, Balıkesir in the academic term of 2006-2007.
Findings and Discussions: Students‟ responses given to the conceptual understanding test before teaching show that 43% and 55% of the students suggested scientifically unacceptable responses in experimental and control groups respectively. It is revealed that most of the students in this group (38% in the experimental and 35% in the control groups) attribute the phenomenon of colouring on soap bubble to dispersion of white light to its colours as a result of different refraction of seven colours existed within the white light. Majority of the students answered the question by using their ideas about geometrical optics. In the post test, 57% of the experimental and 25% of the control group students reasoned a scientifically acceptable and full argument in their responses. Although some control group students (e.g. K3 and K1) responded full and partially correct arguments in the post test, they failed to explain what caused the colouring on the bubble and the effect of bubble thickness on interference in the interviews. Such an important finding with regard to teaching points out the need of putting an emphasis on the relationships between path difference and bubble thickness as well as path difference and wave length. One of the most important findings emerged after teaching was that 25% of the control group students developed a hybrid model so as to explain the colouring on the soap bubble. Those students, who used the wave model of light in conjunction with the previously taught geometrical optic ideas, showed that they would continue to use explanations by referring to old ideas, which were found to be easy for themselves, when the recently introduced ideas were not internalized as Tytler (2002) pointed out.
Conclusions and Recommendations: Control group students were frequently observed to have a difficulty in explaining the order of bright and dark fringes on a bubble and they came up with misconceptions, which had not been reported in the literature, such as „a dark fringe is formed only on the thinnest part of the bubble‟ and „an ordinary image seen on the glass is formed as a result of interference between incident and reflected light rays‟ in the post interviews. It is therefore suggested that instructors should be careful in making generalizations during activities by showing that even bright-dark fringes can be observed in ascending thickness of the bubble after the demonstration of the dark fringe‟s formation on the thinnest part of the bubble. Although hybrid models were proposed by students in single and double-slit interference topics and those were reported by Ambrose et al.(1999), Wosailait et al. (1999) and Author (2012), a hybrid model about thin film interference has been revealed firstly in this study. Thus, researchers, who are interested in conducting a research on the thin film interference topic, should take into account designing activities that prevent the development of the hybrid model described in this study. This study has been an attempt from „cold conceptual change‟ (Pintrich et al., 1993) towards „warm conceptual change‟ and such a „warm trend‟ in conceptual change start to be the rationale of the recent studies in science education area. Effectiveness of the designed conceptual change model, which was based on conflict between ideas and supported with motivational strategies in this study, can be examined by applying this model in teaching of other science topics and by comparing obtained results with previous studies.
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Abstract (Original Language):
Kavramsal değişim stratejilerinden fikirler arası çatışmaya dayalı olarak tasarlanan ışığın ince zarda girişimi konusuna ait öğretimin, öğrencilerin kavramsal anlamaları üzerinde olumlu bir etkisi olup olmadığı, ön test son test kontrol gruplu yarı deneysel desenin uygulandığı bu araştırma ile belirlenmeye çalışılmıştır. Araştırmada veri toplama aracı olarak; hazır bulunuşluk testi, kavramsal anlama testi ve yarı yapılandırılmış görüşmeler kullanılmıştır. Verilerin analizi sonucunda, öğretim öncesinde, öğrencilerin ince zarda girişimi büyük oranda geometrik optik bilgilerini kullanarak beyaz ışığın içeriğindeki yedi rengin farklı kırılması sonucu renklerine ayrılmasına dayandırdıkları bulunmuştur. Öğretim sonrasında ise kontrol grubu öğrencileri sabun köpüğündeki renklenmeyi açıklamak için geometrik optik ile ışığın dalga modelini bir arada kullanarak hibrit model geliştirmişlerdir. Bu öğrenciler köpüğün renklenmesi olayını ışığın köpük üzerinde girişim yapması, aydınlıkların yapıcı girişim, karanlıkların bozucu girişim sonunda meydana gelerek dalga modeli ile açıklarken, renklenmenin nedenine inildiğinde öğretim öncesi fikirlerini kullanarak geometrik optik bilgilerine dönüp ışığın kırılması ile farklı renklerin görüleceğini belirtmektedirler. Kontrol grubu öğrencilerinin aydınlık karanlık saçakların zar üzerindeki dizilimlerini açıklama konusunda zorlandıkları gözlenmiş ve karanlık saçağın sadece zarın en ince kısmında oluşacağı şeklinde daha önce alan yazında görülmeyen kavram yanılgısına rastlanmıştır. Öğretim sonrasında kavramsal değişim stratejisinin benimsendiği deney grubundaki öğrenciler zar üzerinde neye göre renklenmenin olduğunu ve zar kalınlığının girişime etkisini tam olarak açıklayarak kontrol grubundaki öğrencilere göre kavramsal anlamalarının üst düzeyde olduğunu göstermişlerdir.
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