| Students' understanding of nature of science(NOS)is a critical component of scientific literacy.The NOS teaching has always been the focus of science education research at home and abroad.At present,there are two major categorizations of research on NOS in China.One focuses on teacher's application of NOS teaching approach and model or improving teacher's understanding of NOS in order to promote students' conceptions of NOS.The other one focuses on teachers' NOS teaching behavior: exploring the relationship between teachers' view of NOS and their behavior;constructing teacher's NOS teaching behavior and words.However,the effectiveness of the teachers NOS teaching from the perspective of students was never studied in the second type of research.In fact,the transformation of teacher's understanding of NOS is a complicated process which would be influenced by teachers' NOS teaching belief,embodiment of NOS in textbooks and curriculum standards,students' preconceptions about NOS and teachers' understanding and application of teaching strategies and more.As a result,based on the perspective of PCK for NOS,through the collection and analysis of teachers' teaching plan,classroom record,interviews,and the comparison of students' view of NOS before and after NOS teaching,a middle school science teacher and her students will be the research objects.The situation is to comprehensively evaluate the transformational effectiveness of the teacher's understanding of NOS.More specifically,to evaluate whether the teacher conveys her understanding of NOS into actions that benefit students' understanding of NOS.In addition,the factors that influence the teacher's practice will be studied.The research mainly goes through two stages: the first stage is construction of theoretical framework and definition of core concepts.Based on the previous research,the author designed the teacher's framework of PCK for NOS,key points for analyzing lesson plans and analytical framework for NOS teaching behavior.Under the guidance of an expert in the field of NOS,the author designed questionnaire about students' understanding of NOS,teacher's interview outline and so on.The second stage is practical research: tracking the teacher's NOS teaching and implementing NOS questionnaire to students before and after teacher's teaching.The research results are as follows:1.Students' understanding of some aspects of NOS presents an unbalanced improvement: There is a slight improvement in some aspects of NOS,such as “empirical”,“creative and imaginative”,“social and cultural embeddedness” and “distinction between observation and inference”.But there is no significant change in the dimensions of “temporary” and “distinction between scientific theories and laws” before and after teaching intervention.And there is a little decline in the aspect of “subjectivity”.Moreover,the students' understanding of NOS has certain similarities with teacher's NOS teaching behavior in all dimensions.2.During the research process,the teacher's PCK for NOS is dynamic and developing.However,there are also some problems and factors that affect the transformation of teachers' understanding of NOS: the teacher has insufficient understanding of explicit teaching;the neglect of students' preconceptions about NOS before teaching;lack of evaluating students' view of NOS;the major contents of examination is students' memorization and understanding of science knowledge;and "teacher-centered" teaching habits etc.After the research,the author finds that the teacher with contemporary understanding of NOS are a necessary but insufficient condition to enhance students' understanding of NOS.What is directly related to students' NOS conceptions is the teacher's teaching behavior.And the transformation of teachers' understanding of NOS is a process of integration.The knowledge of each component in PCK for NOS interacts with each other.The lack of knowledge of some components will further affect the transformation of teachers' understanding of NOS. |
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