Rasch model analysis of Hong Kong senior secondary school students' views and understandings of nature of science

Empirical Research Background: Adequate understandings of ‗Nature of Science‘(NOS) are one of the most commonly adopted learning outcomes for school science education in many nations or regions around the world since 1990s because NOS can empower citizens to properly assess scientific claims for making informed decision and can help students (i) develop a fundamental understanding of the philosophical and sociological role of the scientific theory and process and (ii) enriches their lives. In the Hong Kong new senior secondary curriculum, NOS has acquired a more prominent position in all science subjects. Empirical Research Aims: We aim to assess the corresponding educational goal related to NOS and so we must first develop a valid, reliable, practical and easy-to-analyse research instrument for large-scale probing of students‘ understandings and views of NOS. Empirical Research Sample: By convenience, 14 classes of secondary 5 (grade 11) students in 6 Hong Kong secondary schools were chosen as a teacher in each school was willing to administer the pencil-and-paper questionnaire in their classes. A total of about 460 valid questionnaires were returned. Empirical Research Method: We have made use of 3 cases from history of physical science (to wit, biography of Galileo Galilei, Thomson and Rutherford‘s atomic models, and observation of ―canali‖ in Mars) plus two other historical cases and issues from the biomedical field (to wit, Jenner‘s use of vaccination for immunization against smallpox, and discovery of SARS virus in Hong Kong) to develop a new set of questionnaire research tools for probing the senior secondary students‘ views and understandings of NOS. We had conducted a systematic review of most the past NOS instruments and the major criticisms on past paper-and-pencil NOS questionnaire instruments were properly considered and addressed during the design process. Instead of using the traditional five-option Likert scale response format in the questionnaire, we introduced a new degree of validity (V) which was a six-point scale (V = 0, 1, 2, 3, 4, or 5) for the respondents to indicate the possibility of validity of a given statement. Besides, we also introduced another six-point scale (W = 0, 1, 2, 3, 4, or 5) for the respondents to reflect their understanding of the meaning of the given statement. Empirical Research RASCH: For the first time in the NOS field of research, the partial credit model of the Rasch measurement was employed to analyse (a) the students‘ perceived ability to properly interpret the meaning of the questionnaire items and (b) their understandings and views of NOS. Those surveyed data were also triangulated with the group interviews of a few randomly selected students in each class. Empirical Research Results: Based on the Rasch model analysis, the key findings re-assure the quality of our NOS instrument and provide reliable information on the students‘relative abilities to understand different aspects of NOS. Empirical Research Conclusions: The Rasch model can be used to validate a type of reliability for our NOS instrument and to analyse the data on students' ability to understand the NOS concepts as collected from our NOS instrument. The findings will provide important information for school science teachers to adopt appropriate teaching strategies to nurture their students' proper understanding of NOS.