Developing pck for an explicit nature of science for vietnamese university students in physics teacher education

DEVELOPING PCK FOR AN EXPLICIT NATURE OF SCIENCE FOR VIETNAMESE UNIVERSITY STUDENTS IN PHYSICS TEACHER EDUCATION MRS.. FOR DOCTOR OF PHILOSOPHY IN SCIENCE EDUCATION Thesis Title: Deve

PHYSICS TEACHER EDUCATION

MRS THI PHUONG THAO DO

A THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

KHON KAEN UNIVERSITY

2015

DEVELOPING PCK FOR AN EXPLICIT NATURE OF SCIENCE FOR VIETNAMESE UNIVERSITY STUDENTS IN

PHYSICS TEACHER EDUCATION

MRS THI PHUONG THAO DO

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN SCIENCE EDUCATION GRADUATE SCHOOL KHON KAEN UNIVERSITY

2015

FOR DOCTOR OF PHILOSOPHY

IN SCIENCE EDUCATION

Thesis Title: Developing PCK for an Explicit Nature of Science for Vietnamese

University Students in Physics Teacher Education

Author: Mrs Thi Phuong Thao Do

Thesis Examination Committee:

Assoc Prof Dr Kongsak Thathong Chairperson Asst Prof Dr Chatree Faikhamta Member Prof Dr Lilia Halim Member

Asst Prof Dr Chokchai Yuenyong Member

Thesis Advisor:

……… Advisor (Asst.Prof Dr Chokchai Yuenyong)

……… ……… ……… (Assoc.Prof.Dr Surasakdi Wongratanacheewin) (Asst.Prof.Dr Maitree Inprasitha)

Dean, Graduate School Dean, Faculty of Education

Copyright of Khon Kaen University

2.1.2 Roles of NOS in teaching and learning science 14

2.2.1 What is Pedagogical Content Knowledge? 19

2.3 Pedagogical Content Knowledge for Nature of Science 25

2.3.3 Some specific strategies to introduce NOS 28

2.3.5 Knowledge of assessment of PCK for NOS 32

3.1 Methodology and Paradigms for research 37

3.2.2 Strategies for ensuring transferability 443.2.3 Strategies for ensuring dependability 453.2.4 Strategies for ensuring confirmability 45

4.1 General history of Vietnam science education 554.2 Impact of the traditional agriculture and Confucianism paradigm 594.3 Impact of socialism Marxism – Leninism, Ho Chi Minh‘s thoughts 60

4.5 NOS issue in the constructivist learning environment in Vietnam 70CHAPTER V DEVELOPING NOS ASSESSMENT INSTRUMENT FOR

5.1 Dilemma of Examining Understanding of Nature of Science in Vietnam 765.1.1 Criticisms in NOS understanding assessment 77

5.1.2.3 Type of instrument 835.1.2.4 Other social and cultural aspects 845.2 Develop NOS assessment tool to use in Vietnam 865.2.1 Analysis and selection of a NOS assessment tools 865.2.2 Experiences from the NOS workshop in Vietnam 90

5.2.2.2 Vietnamese views of NOS and of NOS teaching from the

5.2.2.3 Results from the workshop discussion and activities: 1005.2.3 The VN-VNOSQ and its analyzing and validation process 104CHAPTER VI INVESTIGATE VIETNAMESE PHYSICS STUDENT TEACHERS‘

6.1 General NOS views from Vietnamese Physics student teachers 1146.2 NOS 1: Scientific uncertainty/ tentativeness 117

6.6 NOS 5: Scientific knowledge is theory-laden 1216.7 NOS 6: Science is creative and imaginative 1226.8 NOS 7: Social and cultural impacts on science 124

7.1.1.1 A1: Discussion: What is science? What is not science? 134

7.1.1.3 A3: Four theories about the origin of the moon 137

7.1.1.5 A5: Practice observation and inference - Illusion and magic 141

7.1.1.6 A6: Missing facet of a dice 143

7.1.1.8 A8: Card activity - the scientific community 145

7.1.1.10 A10: Draw a picture of a scientist If you are a scientist, what

8.1 Participants‘ general profile in this phase 163

8.3 Develop PCK for explicit NOS through microteaching 1668.4 Develop PCK for explicit NOS through real teaching in group work 1798.4.1 Topic 1: Observation and Inference in Physics 181

8.4.2 Topic 2: Physics and creativity and imagination 190

8.4.4 Topic 4: NOS aspects that can be withdrawn from the life and career

8.4.5 Conclusions from the PCK for explicit NOS development through real

8.5 Develop PCK for explicit NOS in pre-service teaching 197

8.6 Conclusion on the development of PCK for explicit NOS 211

Thi Phuong Thao Do 2558 การพัฒนาศาสตร์การสอนเนื้อหาวิชา (PCK) เพื่อการสอน

เนื้อหาวิชา (PCK) เพื่อการสอนธรรมชาติวิทยาศาสตร์อย่างชัดแจ้ง ในระหว่างที่นักศึกษา

กลุ่มเป้าหมายเรียนวิชานี้ พวกเขาได้พัฒนาศาสตร์การสอนเนื้อหาวิชา (PCK) เพื่อการสอน

ธรรมชาติวิทยาศาสตร์อย่างชัดแจ้ง โดยการเขียนแผนการสอนที่เน้นที่ความสอดคล้องธรรมชาติ วิทยาศาสตร์ การปฎิบัติการสอนตามแผนการสอนที่พัฒนาขึ้น และการทบทวนและปรับปรุง แผนการสอน การวิเคราะห์พัฒนาศาสตร์การสอนเนื้อหาวิชา (PCK) เพื่อการสอนธรรมชาติ

วิทยาศาสตร์ ท าโดยใช้วิธีการที่หลากหลาย ได้แก่ การใช้ CoRe ของ Loughran, Mulhall, & Berry (2004) การวิเคราะห์แผนการสอน, การสะท้อนผลแผนการสอนของตัวเองและการให้เพื่อนหรือ บุคคลอื่นที่เกี่ยวข้องสะท้อนผล แผนการสอน, และวิเคราะห์จากพฤติกรรมการแสดงออกและการ ปฎิบัติการสอนของนักศึกษาครูในการทดลองสอน สุดท้าย เพื่อเป็นการประเมินว่านักศึกษาครู สามารถพัฒนาศาสตร์การสอนเนื้อหาวิชา (PCK) เพื่อการสอนธรรมชาติวิทยาศาสตร์อย่างชัดแจ้ง ให้เหมาะกับเนื้อหาเฉพาะและบริบทได้ ในขั้นนี้จึงให้นักศึกษาครูกลุ่มเป้าหมาย ได้พัฒนาอย่าง ต่อเนื่องในสถานการณ์จริง เกี่ยวกับศาสตร์การสอนเนื้อหาวิชา (PCK) เพื่อการสอนธรรมชาติ วิทยาศาสตร์อย่างชัดแจ้ง กลุ่มเป้าหมาย ที่เหลือ 8 คน ในขั้นนี้ ได้ปฎิบัติการสอนเพื่อการสอน ธรรมชาติวิทยาศาสตร์อย่างชัดแจ้ง ในโรงเรียนจริง โดยนักศึกษาทั้ง 8 คน นี้ได้เป็นนักศึกษา ฝึกสอน โดยกระจายไปลงปฎิบัติการสอนในระดับมัธยมปลาย ในเมืองเกิ่นเทิง และจังหวัดวินลอง เป็นระยะเวลา 3 เดือน ผลการวิจัยพบว่า นักศึกษากลุ่มเป้าหมายส่วนใหญ่สามารถเตรียมการสอน และด าเนินการสอนธรรมชาติวิทยาศาสตร์แบบชัดแจ้งได้อย่างมีประสิทธิภาพ ได้ด้วยตัวเองและ สอดคล้องกับบริบทของโรงเรียนที่ตัวเองฝึกสอน นอกจากนั้น นักศึกษาฝึกสอนกลุ่มเป้าหมาย ยังมี ทัศนคติที่ดีมากต่อแนวทางการสอนธรรมชาติวิทยาศาสตร์อย่างชัดแจ้ง และดูเหมือนว่า นักเรียนที่ อยู่ในชั้นเรียนฟิสิกส์ที่เน้นสอนธรรมชาติวิทยาศาสตร์แบบชัดแจ้ง มีความกระตือรือร้นและสนใจ เรียนมากกว่า เมื่อเทียบกับการสอนฟิสิกส์ที่เน้นเพียงเนื้อหาอย่างเดียว ข้อจ ากัดที่ส าคัญในการบูร ณาการธรรมชาติวิทยาศาสตร์ในหลักสูตรฟิสิกส์ของเวียดนามคือ เป็นหลักสูตรที่เน้นเนื้อหาวิชา ข้อจ ากัดเรื่องเวลา และประเด็นเกี่ยวกับผู้มีอ านาจซึ่งครูต้องรอการสั่งการจากเบื้องบน จึงท าให้ นักศึกษากลุ่มเป้าหมายไม่สามารถสอนธรรมชาติวิทยาศาสตร์แบบชัดแจ้งในชั้นเรียนที่เน้นเนื้อหา ตามหลักสูตร ขณะที่รอการปฏิรูปการศึกษาในเวียดนามในอีกไม่กี่ปีข้างหน้า กระทรวงศึกษาธิการ และผู้มีส่วนเกี่ยวข้องควรท าให้หลักสูตรมีความยืดหยุ่นมากขึ้นกว่าเดิม ซึ่งอาจจะเป็นหลักสูตรชั้น เรียนพิเศษ แล้วครูเวียดนามจึงจะสามารถด าเนินการสอนธรรมชาติวิทยาศาสตร์ได้ โดยอาจจะสอน ธรรมชาติของวิทยาศาสตร์ 2 – 3 ครั้ง ในแต่ละภาคการศึกษา เพื่อจะได้ทบทวนและหาจุดแข็งใน การสอนฟิสิกส์ส าหรับนักเรียนขณะที่มีการเรียนการสอนธรรมชาติวิทยาศาสตร์แบบชัดแจ้ง เมื่อ พิจารณาด้านต่างๆของธรรมชาติวิทยาศาสตร์ที่ Lederman (2007) เสนอไว้ว่านักเรียนระดับ

การศึกษาขั้นพื้นฐานควรศึกษาธรรมชาติวิทยาศาสตร์ในประเด็นใดบ้าง ก็เห็นได้ว่า นักการศึกษา ทั้งหลายก็เห็นเหมือนกันว่าประเด็นเหล่านี้ ควรให้ผู้เรียนได้เรียนครบทุกด้านของธรรมชาติ วิทยาศาสตร์ ก่อนจบหลักสูตรมัธยมปลาย

Thi Phuong Thao Do 2015 Developing PCK for an Explicit Nature of Science for

Vietnamese University Students in Physics Teacher Education Doctor of

Philosophy Thesis in Science Education, Faculty of Education, Khon Kaen University

Thesis Advisor: Asst Prof Dr Chokchai Yuenyong

ABSTRACT

The Nature of Science (NOS) has been advocated as an important learning goal

in science education for more than a century with certain contributions to science teaching and learning Nonetheless, what, how and how much NOS should be integrated in the science curriculum of each country cannot be a benchmark due to the influence of culture and society This study aims to have some Physics student teachers developing several ways to teach NOS effectively and explicitly under Vietnam‘s Physics curriculum, which means developing their pedagogical content knowledge (PCK) for NOS explicit teaching The preparations for the final objective include the studies on the current NOS views of Vietnamese Physics student teachers and the development of a more proper understanding of NOS for the participants The participants for the NOS views survey are two hundred and seventy eight 3rd year and last year students in Physics Teacher Education program, School of Education, Can Tho University Among them, there are 11 volunteered to attend the research course First, a four-week NOS workshop was organized to develop these student teachers‘ understanding of NOS Pre-test and post-test were used to assess the NOS conception change to make sure that all the participants have an adequate understanding of NOS before developing their PCK for NOS After that, a microteaching course on PCK for explicit NOS in three months was undertaken During this course, the student teachers developed their PCK for teaching NOS explicitly by planning the NOS-focused lessons, practicing their lessons, reviewing and revising the lesson plans The PCK for NOS was assessed by using multiple methods, including using the CoRe form (Loughran, Mulhall, & Berry, 2004), analyzing the lesson plans, self-review and peer-review process, and the analyzing teachers‘ general manner of addressing NOS in their microteaching presentations A more realistic PCK for explicit NOS was

continue developed by providing opportunities for the remaining 8 participants to teach NOS explicitly in real situations Finally, the developed PCK for explicit NOS was tested its effectiveness and feasibility during the three months pre-service teaching when these participants became pre-service teachers in several upper-secondary schools in Can Tho city and Vinh Long province Results from this study were prominent where most of the participants can organize and perform the NOS explicit teaching effectively by their own in the schools that they practiced their NOS teaching as well as at the schools where they worked as the pre-service teachers Moreover, the participants indicated very positive attitude toward the NOS explicit teaching approach since the students in their classes were always being more active and interested in the NOS-Physics lessons than the Physics content-oriented lessons The biggest limitation of the integration of NOS in Vietnam‘s Physics curriculum caused by the rigid, content-based curriculum, limitation of lesson time, and authority issues that make the participants impossible to teach NOS explicitly in the curriculum-based classes While waiting for the next reform in Vietnam education, Vietnam‘s teachers can organize their NOS, extra-curriculum classes, which can be organized two to three times every semester, to review and strengthen Physics problems for the students while teaching NOS explicitly and effectively Considering the number of NOS aspects suggested by Lederman (2007) to be taught for K-12 students, educators actually only need this to finish all the NOS goals before the graduation of upper secondary students

DEDICATION

The Present Thesis is Greatly Dedicated

to my Family and the Entire Teaching Staff

ACKNOWLEDGEMENTS

I would like to express my deepest and sincere gratitude to Khon Kaen University and Faculty of Education of Khon Kaen University for awarding me a scholarship to study

I am also very grateful to my advisor, Asst Professor Dr Chokchai Yuenyong for his kindness in providing an opportunity to be his advisee Many thanks for his valuable supervision, suggestions, encouragement, support, guidance and criticism throughout the course of my study

I am very appreciating my other teaching staff, especially Assoc Professor Dr Kongsak Thathong and Asst Professor Dr Paisan Suwannoi for their teaching instructions and valuable advices, kindness, useful comments and suggestions

Sincere thanks and appreciation are also due to my graduate committee, Assoc Professor Dr Kongsak Thathong, Asst Prof Dr Chatree Faikhamta, Prof Dr Lilia Halim, Dr Jiradawan Huntula, and Asst Prof Dr Chokchai Yuenyong for their helpful suggestions

I also would like to thank all of the participants from Department of Physics Teacher Education, School of Teacher Education, Can Tho University Also, I am highly appreciated the stake holders, the teachers, and the students in these upper secondary schools that joined the research: the Demonstration School of Can Tho University, Nguyen Viet Hong School of Can Tho city, Nguyen Viet Dung School of Can Tho city, Tran Dai Nghia School of Can Tho city, and Binh Minh School of Vinh Long province Without your contributions, the research could not be done

I also want to thank my classmates and Thai friends in Science Education program Thank you for making me feel like I am at home during the time I was in Thailand You are all wonderful friends Hope our friendship is forever

Finally, I would like to express my sincere gratitude and appreciation to my family and my family in-law for supporting me to study abroad I really thank my husband and my little daughter who gave me the brave and the support I need to study

Thi Phuong Thao Do

LIST OF TABLES

Page

Table 2: 14 aspects of NOS that consensus from 8 international standard documents 13Table 3: Comparison of agreed NOS elements indicated in two previous studies,

Table 4: Subjects in Physics Teacher Education programs, SoTE, CTU that relates to

Table 5: PCK Evidence Reporting Table (Park & Oliver, 2008) 34Table 6: NOS elements suggested by Chinese science teacher educators as NOS content to be taught to prospective science teachers (Wan et al., 2013) 65Table 7: Actual and preferred learning environment through the lens of constructivist

in Physics Teacher Education program in Can Tho University, Vietnam Results from Constructivist Learning Environment Survey questionnaire 72Table 8: Some background information of the interviewees 74Table 9: Some validated instruments to assess NOS as considered by Lederman

Table 10: Things to be considered careful during the questionnaire development

Table 11: A slightly revised VNOS-C of Lederman et al (Lederman et al., 2002),

Table 12: Workshop activities and related NOS aspects 91Table 13: NOS aspects that Vietnamese participants related to in their responses for

Table 14: Summary of Vietnamese common ―nạve‖ views of NOS 100Table 15: Vietnamese View of Nature of Science Questionnaire (VN-VNOSQ) 106Table 16: Numbers and percentage of supporting or alternative ideas received from

Table 17: NOS aspect relate to the VN-VNOSQ items with the description 111Table 18: Vietnamese Physics student teachers‘ ideas for each statement 114Table 19: Percentage of views of Vietnamese Physics student teachers on each NOS

Table 20: Vietnamese Physics student teachers‘ views toward the ―truth‖ and

Table 21: Ideas of Vietnamese Physics student teachers on from which a scientific

Table 26: NOS activities presented in the training course 133Table 27: Pre/Post-test comparison, from item Q1-1 to item Q1-8 153Table 28: Pre/Post-test comparison, from item Q1-9 to item Q3-1 154Table 29: Pre/Post-test comparison, from item Q3-2 to item Q6 155Table 30: Pre/Post-test comparison, from item Q7-1 to item Q11 156Table 31: Summary the general percentage of pre and post NOS views from the

Table 32: The final ratios of the participants for each NOS aspect 160Table 33: Each participant‘s general view on each NOS aspect 161

Table 37: Compare and contrast the PCK for tentative NOS of two participants

presented in CoRe forms based on the five domains of PCK of Magnuson et al (1999)

172Table 38: A CoRe form with many of the responses are too general to be interpreted

175

Table 40: Pearl‘s ideas of PCK for NOS from the think aloud protocol 177Table 41: List of NOS classes that practiced by the participants 180Table 42: Observation and inference in Physics – lesson plan 1 181

Table 43: Part of the lesson plan 2 for topic 1 - Observation and inference in Physics

185Table 44: Observation and inference in Physics – lesson plan 3 188Table 45: Physics and creativity and imagination - lesson plan 190Table 46: The observed classes of the pre-service teachers 198

LIST OF FIGURES

Page

Figure 2: A knowledge bases for teaching Figure obtained from Park and Oliver

Figure 3: A simplified version of PCK model for science teaching, picture taken from

Figure 4: Hexagon model of pedagogical content knowledge for science teaching of

Figure 5: Teachers‘ PCK for NOS Figure obtained from Hanuscin, Lee, and Akerson

Figure 6: Content Representation (CoRe) form of Loughran et al 35

Figure 7: A scheme for analyzing assumption about the nature of social science

Figure 8: The disciplines that add to understanding of the nature of science 54

Figure 9: Constructivist Learning Environment Survey results from student teachers

of Can Tho University Physics Teacher Education program 73

Figure 10: A man‘s face through different observational devices (1) 93Figure 11: The false hierarchical relationship between facts, hypotheses, theories and laws, which was used by a Vietnamese participant to demonstrate that ―theory will

Figure 12: A man‘s face through different observational devices (2) 135

Figure 14: Some typical pictures from clip ―Impossible motion: magnet-like slopes‖

Figure 15: Some typical pictures from clip ―Impossible motion: magnet-like slopes‖ with a different angle of view (TheIllusioncontest, 2010) 142Figure 16: A group of participants is discussing and taking notes on how they will fill

Figure 17: Model of some black boxes that contain the weighted objects at different

Figure 18: The participants are working on the ―black‖ box activity 145Figure 19: Several pictures of ―a scientist to be‖ drew by the participants The

sentence in the last picture means ―Maybe look like Einstein…‖ 148Figure 20: The smiles on the student teachers‘ and student‘s face in a NOS activity

183Figure 21: Two students are presenting the change in knowledge about the earth 194

Figure 26: A group of students in Pearl‘s class are doing the heat transfer experiment

208Figure 27: A group of students in Tiffany‘s class doing the heat transfer experiment

210Figure 28: Tiffany and Chris are guiding the students in two different NOS activities

210Figure 29: A framework of PCK for explicit NOS at Physics specific PCK in

Figure 30: The participants are working and discussing 231

Figure 32: Put the fish into the fishbowl - The formation of images on the retina 234Figure 33: Newton‘s color disc - The formation of white light 234

Figure 36: Stewing through a balloon without explosion 235

Figure 38: A student teacher is instructing students to observe a drop of water falling

Figure 39: A student teacher is instructing students to make an observation with hands

236

Figure 42: Students make an observation by tasting 237

Figure 47: Decorating and balancing a butterfly (or a clown) 239Figure 48: Dropping paper clips on the water surface 240

Figure 51: Students present about the tentative nature of science based on the history

Figure 52: Students present about the lesson learnt from the famous Physicists and

LIST OF ABBREVIATIONS

CoRe: Content Representation

CTU: Can Tho University

MOET: Ministry of Education and Training

NOS: Nature of Science

PaP-eR: Professional and Pedagogical experience Repertoire

PCK: Pedagogical Content Knowledge

PTE: Physics Teacher Education

SoTE: School of Teacher Education

SMK: Subject Matter Knowledge

VN: Vietnam

VN-VNOSQ: Vietnamese View of Nature of Science Questionnaire

CHAPTER I INTRODUCTION

This chapter will provide background and rationale of the study, to indicate the importance for conducting the research with its own scope and expectation From this, research questions and research objectives were derived

1.1 Background and rationale of the study

History and philosophy of science, in which nature of science is an essential part, has been considered having important implications for teaching science (Hodson, 2009; Niaz & Maza, 2011) The term nature of science typically refers to the values and assumptions inherent to scientific knowledge and the development of scientific knowledge (Lederman & Lederman, 2004) In other words, ―through multiple lenses,the nature of science describes how science functions‖ (McComas, Clough, &

Almazroa, 2002, p.5) Matthews (1994) stated that ―today it is a major goal, if not the

major goal, of science education‖

The nature of science (NOS) has been advocated as an important learning goal

in science education for more than a hundred years (Central Association for Science and Mathematics Teachers 1907) McComas et al (2002) argued that ―the nature of science is a fundamental domain for guiding science educators in accurately portraying science to students‖ and the lack of NOS understanding is ―potentially harmful, particularly in societies where citizens have a voice in science funding decisions, evaluating policy matters and weighing scientific evidence provided in legal proceedings‖ Due to Driver et al (Driver, Leach, Millar, & Scott, 1996), NOS has important contributions to students in 5 aspects that were briefly summarised by Firestone et al (Firestone, Wong, Luft, & Fay, 2012, p 190) as the following:

1 Utilitarian: to make sense of science and technology

2 Democratic: for informed decision making

3 Cultural: to value science in culture

4 Moral: to understand the moral norms of science

5 Science learning: to facilitate learning science

On science teaching and learning, McComas et al (McComas, Almazroa, & Clough, 1998) argued that understanding NOS will: 1) enhance the learning of science content; 2) enhance understanding of science; 3) enhance interest in science; 4) enhance decision making; and 5) enhance instructional delivery It can be said that

in science education, NOS is an irremovable part because, more or less, assumptions about NOS will be gradually formed by students and teachers

Since the 1990s, some organizations in USA such as the American Association for the Advancement of Science (AAAS, 1990a, 1993) and the National Research Council (NRC, 1996) already considered that understanding tenets of scientific inquiry and nature of science are at the core of scientific literacy In other words, ―a scientifically literate student would be able to be adept in knowing both content knowledge and nature of science knowledge The purpose of teaching nature of science knowledge is to provide students with knowledge about the endeavour of science and how science content knowledge has been generated and validated‖ (Peters, 2012, p 882) NOS has been advocated as a critical educational outcome by various science education reform documents worldwide, including the countries such

as Australia, Canada, South Africa, United Kingdom, United States (Lederman, 2007) Nowadays, the nature of science presents as an important part in the science curriculum of many countries such as America, Australia, New Zealand, etc (for information see, for examples, AAAS, Center for Curriculum Materials in Science; ACARA, The Australian Curriculum; TKI, The New Zealand Curriculum Online) Even though in the scholar community, the nature of science is still controversial because NOS is a complicated notion which ―blends aspects of various social studies of science including the history, sociology, and philosophy of science combined with research from the cognitive sciences such as psychology…‖ (McComas et al., 2002, p 4) Like scientific knowledge, conceptions of the nature of science are tentative and dynamic (Lederman, Abd-El-Khalick, Bell, & Schwartz, 2002) The specific NOS aspects are still controversial as there are many ways to categorize them (AAAS, 1990b; Lederman, 1999, 2007; Lederman & Lederman, 2004; McComas, 1996, 2000; McComas et al., 1998; Reneé S Schwartz & Lederman, 2002)

Nevertheless, they also argued that ―one of the central responsibilities of science teachers is to provide an accurate description of the function, processes and limits of science rather than to engage students in the somewhat arcane arguments that occur among philosophers of science‖ (McComas et al., 2002, p 6) Fortunately, there are consensus views of NOS on some most common and important aspects of NOS

In particular, there are 14 aspects of NOS that may be considered ―consensus‖ from many research as reviewed by McComas et al (1998) Furthermore, based on Lederman (2007), there are 8 aspects of NOS that are considered noncontroversial and accessible to K – 12 students and which are also considered to be relevant to their daily lives They are: 1) tentative (subject to change), 2) empirically based (based on and/or derived from observations of the natural world), 3) subjective (involves personal background, biases) and/or theory-laden; 4) necessarily involves human inference, imagination, and creativity (involves the invention of explanations); 5) socially and culturally embedded, 6) the distinction between observations and inferences, and 7) the functions of and relationships between scientific theories and laws The 8th facet of science that Lederman and his colleagues suggested in this book

is ―there is no single universal step-by-step scientific method‖

As reviewed by Faikhamta (2012), many studies consistently show that science teachers still possess inadequate conceptions of NOS (Haidar, 1999; Lederman, 1992) including that science is an application of technology (Yalvac, Tekkaya, Cakiroglu, & Kahyaoglu, 2007), scientific knowledge is objective and absolute (Akerson & Donnelly, 2008), scientific methods are the only way to gain knowledge (F Abd-El-Khalick & BouJaoude, 1997; Lederman, 1992), science is a step-by-step process, scientific theories are laws that govern the behaviour of scientific phenomena (Haidar, 1999; Lederman, 1992), science, technology and society are independent (Yalvac et al., 2007), and that science teachers seldom integrate aspects of NOS or make it explicit to students in science learning activities (Mellado, Bermejo, Blanco, & Ruiz, 2008)

Erin E Peters, in his study in 2012 to find more empirical evidence that links nature of science knowledge with content knowledge (Peters, 2012) ascertained that students in the explicit NOS teaching group were significantly outperformed the implicit NOS teaching group on both nature of science and content knowledge

assessments Students in the explicit group also demonstrated a greater use of detail in their inquiry work and reported a higher respect for evidence in making conclusions than the implicit group Peters inferred that students in the explicit group of his study were able to acquire more content knowledge because ―the intervention scaffolded their ability to recognize and act on the guidelines of the scientific enterprise Once students attained the understanding of why the processes of science occurred, they were more adept at comprehending and utilizing content knowledge.‖ (Peters, 2012,

p 896) He then suggested that science educators could enhance nature of science instruction using goal setting and self-monitoring of student work during inquiry lessons

In developing countries such as the ASEAN community, the important of NOS and how to teach NOS effectively is an on-going trend of research Thailand, for an example, is on the way to investigate Thai view of NOS, to include NOS in the science curriculum, and to train science teachers how to teach NOS (Buaraphan, 2009a, 2009b; Faikhamta, 2012; Yuenyong & Narjaikaew, 2009) As indicated by Yuenyong and Narjaikaew (2009), Thai science education influenced by educational reform in 1999, in which the goals of science education are shaped by the notion of scientific literacy that emphasizes the scientific knowledge, the nature of science, and the relationship between science technology and society Recently, there is also research about nature of science in Lao People‘s Democratic Republic (Lao PDR) (Sengdala & Yuenyong, 2014)

On the other hand, there are countries such as Vietnam that still not properly consider NOS in the science curriculum From my best knowledge, NOS are mostly implicit in the Vietnamese science curriculum in general and in Physics curriculum in particular A study on part of Vietnamese Physics curriculum, on heat and NOS-related concepts through history of science (Thao-Do & Yuenyong, 2013) confirmed this as those parts contribute to half of the curriculum for grade 8 and grade 10 Physics but there are no explicit messages of NOS It can be argued that NOS is not a learning goal in Vietnam‘s science curriculum Although Vietnamese teachers and students can gain some understanding about NOS through the learning and investigating processes, in Vietnam, NOS is now a ―side learning outcome‖ only

Particularly, from the author‘s own experience, NOS was never taught explicitly in schools and even the author, as a teacher educator, never teach NOS explicitly for the students To my best knowledge, there are no previous published studies on NOS in Vietnam except the recently published paper of the author herself and her co-author (Thao-Do & Yuenyong, 2013)

Our study on Constructivist Learning Environment Survey (Thao-Do, Bac-Ly,

& Yuenyong, 2014) once again confirmed these assumptions Through the lens of constructivist learning, nature of science, which is partially presented in the scientific uncertainty scale, is considered a main part of the learning This scale relate to NOS tentativeness and social – cultural aspects The result scored 3.27/5, which suggests these aspects of NOS are ―sometimes‖ learnt in the classroom Informal conversations with teachers also revealed that the term ―nature of science‖ is strange for teachers and students However, all of them recognize some common detailed aspects of NOS

To continue with the scope of the study, a workshop on NOS at Can Tho University, Vietnam was conducted on March 2013 NOS conceptions were collected and interpreted using VNOS-C of Lederman (Lederman et al., 2002) and workshop discussion The data indicated that no participants, including both the pre-service teachers and the science teacher educators in Can Tho Universiy, currently hold a totally informed view of NOS Some traditional views of NOS are still common in Vietnam All of the participants indicated the common naive views of NOS which belongs to the myths of science that were synthesized by McComas (McComas, 1996) For example, most of the participants hold that some theories will become laws

if scientists have more evidence to prove its rightness and lively argued to protect their ideas during the discussion Some express their hesitation about scientific uncertainty when they said some knowledge will be changed, and some are proved to

be true already More or less, different Vietnamese participants indicated different views and different levels of understanding the nature of science

It can be question that in a country that currently not considers NOS important

as Vietnam, why should we bother to make NOS explicit and integrate NOS in the classroom? The reason is bonding to several different aims of Vietnam‘s education in which constructivist learning is an important consideration As a matter of fact, Vietnam education is moving toward a student-centered teaching and learning with

the constructivist view Considering the Vietnamese educational aims through Vietnam‘s Education Law 2005 (Vietnam's National Assembly, 2005), article 3 stated the nature and principles of education with two main points:

1 Vietnam education system is the socialism education with the quality of people, nation, science, and modern, taking Marxism - Leninism and Ho Chi Minh‟s ideas

as the foundation

2 Educational activities must be carried out according to the principle that study associates with practice, education combines with productive labor, theory reasoning associates with reality, school education combines with family education and social education

(Translated from Vietnamese Education Law 2005, article 3)

From this article, we can see that Vietnamese traditional culture, which means here the moral values of Confucianism and agricultural country, together with Marxism - Leninism and Ho Chi Minh‘s ideas about socialism, with the noticeable ideas of equality, are important foundation of Vietnamese education system The

education system aims to be active, practical, scientific and modern and, as noted before, is on the way of transforming to the student-centered system

To achieve some part of this goal, NOS can be a key to help improve Vietnamese students‘ outcomes because NOS promotes the ideas of creativity, flexibility, social and cultural interactions with science Besides, NOS also promotes attitude toward science and science subjects, which will then promote students‘ interest in science learning Moreover, it may increases high order thinking through students‘ cognition about the process of scientific investigation and scientific knowledge development Application skills can also be developed during the learning inquiry For the teachers who are interested in active learning using constructivism paradigm, some ideas of NOS are essential as they presents in the scientific uncertainty scale of a constructivist learning environment (Taylor & Fraser, 1991; Taylor, Fraser, & Fisher, 1997)

In Physics teaching, based on the arguments of McComas (McComas et al., 1998) and of Driver et al (Driver et al., 1996) NOS can be a key to increase students‘ interest in Physics as well as Physics literacy and skills For examples, NOS can lessen students‘ fear of making mistakes, promote creative and critical thinking, and

create the close relationship between science and life The roles of NOS in teaching and learning science is undeniable since more or less, every science subject must involve some aspects of NOS and since NOS is (at least) a part of the scientific literacy However, whose NOS, which NOS, how much NOS, and how to teach NOS

in each country context, or even in each class remain controversial because NOS itself

is not universal and is affected by the social, political, and cultural traditions of where

it is taught and learnt This study, therefore, will also investigate the social cultural traditions of the context to consider suitable contents, methods, strategies, assessment, and related aspects that may affect NOS teaching and learning

Especially, Physics, although being considered a ―hard science‖ (Mulhall & Gunstone, 2008), is ample of NOS messages and can clearly demonstrate many aspects of NOS For example the 8 NOS aspects that accessible for K12 student as considered by Lederman and his colleagues (Lederman, 2007) can be learnt from Physics as the following:

1 The distinction and relationship between observation and inference (e.g in Physics experiments)

2 The function of, and relationships between scientific theories and laws (Physics laws and theories)

3 Tentative (e.g the Ptolemy‘s planet system v.s Copernicus‘ planet system)

4 Empirically based (in most Physics concept, law, theory development)

5 Subjective and/or theory-laden (e.g the development of the theory of atomic system)

6 Partly the product of human inference, imagination, and creativity (e.g Einstein‘s imagination, inventions of many theories…)

7 Socially and culturally embedded (the religion influence in the ment of Ptolemy‘s planet system – scientific concept at that time)

acknowledge-8 There is no single best scientific knowledge (Physicists can use different methods, range from pure theoretical to pure experimental, to develop knowledge)

These examples are scatteredly presented in the Physics curriculum in Vietnam and/or usually regarded by teachers as a mean of increasing students‘ interest in Physics, however, in an implicit manner, mostly by the presentation of some most

famous scientists‘ portraits and their born – dead information together with some facts

of their inventions without further investigate on the circumstance of their invention

It is clear that history of science is always an important mean to learn about NOS (F

S Abd-El-Khalick & Lederman, 2000; Lonsbury & Ellis, 2002; Rudge & Howe, 2009) and history of Physics is ample of examples about the aspects of NOS, both scientific knowledge and scientific process However, simply telling the story is a waste of chances to develop students‘ higher order thinking skills and/through NOS if

it was not designed in an explicit – reflective manner

1.2 The scope and limitation of the study

This study aims to develop a more proper understanding of NOS and several ways to teach NOS effectively under the Vietnamese Physics curriculum, which means there is a need to develop pedagogical content knowledge (PCK) for NOS teaching and learning Due to a review on the approach of teaching NOS, the explicit approach is considered the most effective way of teaching now (C.Donovan-White, 2006; Khishfe & Abd-El-Khalick, 2002) This study will focus on this approach together with related ways for the most effective suggestions on PCK for NOS in Vietnam The participants are 3rd year and last year students in Physics Teacher Education program, School of Education, Can Tho University At these stages of study, they are learning and practicing pedagogy, thus, possible to adapt new paradigms of education They will be called student teachers in this study They will become Physics teachers in the near future and if they find the ideas of NOS are useful, we can expect that they will introduce NOS to many different schools and provinces Noted that because NOS is an ―extremely new‖ topic in Vietnam which is still not appropriately considered by the government, educators, and society, a start from the in-service teachers may face with significant and unavoidable obstructs from the teachers themselves, the stakeholders and even the society Universities, which are both leading education and research institutions, in this case are maybe the best place

to innovate

This study is not searching the effective explicit PCK for every of the mentioned 8 NOS aspect Instead, there are only some of them which were considered

the most commonly approved by Vietnamese science teachers and pre-service teachers will be practiced These specific aspects will be explored and discussed later

1.3 Research questions

This thesis will answer these questions:

1 What is the picture of NOS of Vietnamese Physics student teachers?

2 How to develop Vietnamese Physics student teachers‘ understanding of NOS and of NOS teaching?

3 How to develop effective PCK of Vietnamese Physics student teachers for NOS explicit teaching?

1.4 Objectives of the research

Leading by the research questions, this study will focus on these objectives:

1 Investigate how Vietnamese student teachers from Physics Teacher Education program view NOS and levels of their understanding of NOS

2 Develop Physics student teachers‘ understanding of NOS and understanding

of PCK for an explicit NOS

3 Develop Physics student teachers‘ PCK for explicit NOS teaching

Besides the physical development, the major purposes of education in Vietnam

are the three domains: Knowledge – Skill – Attitude which the extent are mentioned in

detail in Education Law for all the levels of education: from kindergarten to higher education (Vietnam's National Assembly, 1998a, 2005, 2009) However, looking from the perspective of educators outside of Vietnam, knowledge is the most to be taught in Vietnam (Saito & Tsukui, 2008; Saito, Tsukui, & Tanaka, 2008a) In

several training workshops, the author found the idea that ―Proficiency = Knowledge

+ Skill + Attitude” repeatedly confirmed by Vietnamese teachers and educators

Therefore, NOS was regarded to develop the two currently weak points of Vietnamese education: Skill and Attitude

- Scientific investigation skills: Observation and inference skill

o Observation skills: Using all the senses that necessary for the direct

and indirect observation

o Inference skill: flexible combine different thinking skills in

investigation such as critical thinking, creative thinking, problem solving skill

- Educate attitude towards science:

a) Appreciate scientists and different views on science (although the scientists and the views maybe considered not appropriate now) because science does not include right hypotheses and conclusions The way to construct scientific knowledge requires different point of views to challenge the validity and reliability of knowledge The previous theories are the foundation to build up the later knowledge And because scientific knowledge, although being durable, will be changed

b) Not afraid of making mistake in science and in study (but must try to lessen mistake) because personal bias and human mistake are a part of science and cannot totally eliminated in science Instead, try to learn from mistake

c) Understand that science – technology – society cannot be separated Science is a part of the culture in which it is conducted Science is not for destroying, but for constructing also, based on the demand of the society To make decision in science, scientists must base on the culture and society

d) Know and willing to share and review knowledge from other students (like the way scientist share and review knowledge.)

e) Interest toward science: Science is creative, flexible Science is not stiff and rigid but can be a lot of fun

Noted that it does not mean that knowledge will not be developed here, because NOS is also knowledge, and as proved by Peters (2012), understanding NOS will develop deeper understanding of knowledge In other words, knowledge about NOS is the basement for more important learning outcomes including constructing science knowledge rather than we satisfy with providing someone an informed understanding

of NOS but do not know how to apply NOS in a meaningful way

CHAPTER II LITERATURE REVIEW

This chapter will provide an insight into nature of science, the roles of nature of science in science education, Pedagogical Content Knowledge, and finally some of the Pedagogical Content Knowledge for Nature of Science This background information will be vital to orient the research and provides argumentations for the research methodology, as well as the whole research Information from this chapter is the foundation to develop researcher‘s PCK for NOS then guides the process of developing PCK for explicit NOS for the participants

2.1 Nature of science

2.1.1 What is nature of science?

The phrase Nature of Science (NOS) typically refers to the values and assumptions inherent to scientific knowledge and the development of scientific knowledge (Lederman & Lederman, 2004) ―Through multiple lenses, the nature of science describes how science functions‖ (McComas et al., 2002, p.5) In general, the nature of science refers to key principles and ideas which provide a description of science as a way of knowing, as well as characteristics of scientific knowledge Even though in the scholar community, the nature of science is still controversial (Lederman, 2007) because NOS is a complicated notion which ―blends aspects of various social studies of science including the history, sociology, and philosophy of science combined with research from the cognitive sciences such as psychology…‖ (McComas et al., 2002, p 4) There are many ways to categorize the specific aspects

of NOS (AAAS, 1990b; Lederman, 1999, 2007; Lederman & Lederman, 2004; McComas, 1996, 2000; McComas et al., 1998; Reneé S Schwartz & Lederman, 2002)

Nevertheless, they also argued that ―one of the central responsibilities of science teachers is to provide an accurate description of the function, processes and

limits of science rather than to engage students in the somewhat arcane arguments that occur among philosophers of science‖ (McComas et al., 2002, p 6) Fortunately, there are consensus views of NOS on some most common and important aspects of NOS This study focuses on 7 main aspects that accessible for K12 students suggested by Lederman (2007): 1) tentative (subject to change), 2) empirically based (based on and/or derived from observations of the natural world), 3) subjective (involves personal background, biases) and/or theory-laden; 4) necessarily involves human inference, imagination, and creativity (involves the invention of explanations); 5) socially and culturally embedded, 6) the distinction between observations and inferences, and 7) the functions of and relationships between scientific theories and laws There is also an additional facet of science that Lederman and his colleagues also suggested in this book which is ―there is no single universal step-by-step scientific method‖

Besides Lederman‘s NOS categorization, AAAS (1990b) categorized the NOS components into three groups (table 1):

Table 1: AAAS NOS elements

The scientific world view Scientific inquiry The scientific enterprise

The world is understandable

Scientific ideas are subject to

change

Scientific knowledge is durable

Science cannot provide

complete answers to all

questions

Science demands evidence Science is a blend of logic and imagination

Science explains and predicts Scientists try to identify and avoid bias

Science is not authoritarian

Science is a complex social activity

Science is organized into content disciplines and is conducted in various institutions There are generally accepted ethical principles in the conduct

of science Scientists participate in public affairs both as specialists and as citizens

Note: In later studies, these three groups could be named as scientific knowledge, scientific investigation, and scientific enterprise (Wan, Wong, & Zhan, 2013)

There are other ways to categorize NOS aspects, one of them is the list of McComas et al (McComas et al., 1998) in which there are 14 aspects of NOS that he considered ―consensus‖ from many research (table 2)

Noted that there are actually no distinct borders among the aspects, as sometimes one aspect of NOS shares the ideas from two or more categories For instance, if we look at the comparison of agreed NOS elements from previous studies made by Wan et al (2013), we can see that sometimes there is one element of NOS in

a study contains multiple elements of NOS in another study such as the idea of

―Cooperation and collaboration in science‖ from the work of Osborne et al (Osborne, Collins, Ratcliffe, Millar, & Duschl, 2003) may include most of the aspects from

―scientific enterprise‖ from the review of McComas and Olson (McComas & Olson, 1998) (see table 3)

Table 2: 14 aspects of NOS that consensus from 8 international standard documents

1 Scientific knowledge while durable, has a tentative character

2 Scientific knowledge relies heavily, but not entirely, on observation, experimental evidence, rational arguments, and skepticism

3 There is no one way to do science (therefore, there is no universal step-by-step scientific method)

4 Science is an attempt to explain natural phenomena

5 Laws and theories serve different roles in science, therefore students should note that theories do not become laws even with additional evidence

6 People from all cultures contribute to science

7 New knowledge must be reported clearly and openly

8 Scientists require accurate record keeping, peer review and replicability

9 Observations are theory-laden

10 Scientists are creative

11 The history of science reveals both an evolutionary and revolutionary character

12 Science is a part of social and cultural traditions

13 Science and technology impact each other

14 Scientific ideas are affected by their social and historical milieu

Table 3: Comparison of agreed NOS elements indicated in two previous studies, obtained from Wan et

al (2013)

McComas and Olson (McComas & Olson, 1998) Osborne et al (Osborne et al., 2003) Scientific knowledge

Scientific knowledge is tentative

Change in science occur gradually

Science and certainty Historical development of scientific knowledge

Scientific investigation

Science is an attempt to explain phenomena

Scientist are creative

Science relies on empirical evidence

Scientists require replicability and truthful reporting

New knowledge must be reported clearly and openly

Analysis and interpretation of data Creativity

Scientific method and critical testing Science and questioning

Hypothesis and predication Diversity of scientific thinking

Scientific enterprise

Science is part of social tradition

Science has played an important role in technology

Scientific ideas have been affected by their social and

historical milieu

All culture contributes to science

Scientists make ethical decision

Science have global implication

Cooperation and collaboration in science

Noted:

- McComas and Olson (McComas & Olson, 1998) reviewed eight science standards documents

in the Western world, including the United States, Australia, Canada, England and New Zealand

- Osborne et al (Osborne et al., 2003) The participants of this study were twenty-three Western leading scientists, historians, philosophers and sociologists of science; science teacher educators; experts engaged in the public understanding of science or science communication; and expert science teachers

2.1.2 Roles of NOS in teaching and learning science

History and philosophy of science, in which nature of science is an essential part, has been considered having important implications for teaching science (Hodson, 2009; Niaz & Maza, 2011) ―Through multiple lenses, the nature of science describes how science functions‖ (McComas et al., 2002, p.5) About the important of nature of science, from Matthews (1994) which being cited by Alters (1997, p 39)

―today it is a major goal, if not the major goal, of science education‖ McComas et al (2002) argued that ―the nature of science is a fundamental domain for guiding science educators in accurately portraying science to students‖ and the lack of NOS understanding is ―potentially harmful, particularly in societies where citizens have a voice in science funding decisions, evaluating policy matters and weighing scientific evidence provided in legal proceedings‖ It is now broadly accepted in science educators‘ community that NOS is an essential part of science teaching with important implications (Niaz & Maza, 2011)

NOS focuses on scientific literacy, high order thinking skills (critical and creative thinking), decision making, attitude, collaboration and communication in science Understanding tenets of scientific inquiry and nature of science are at the core of scientific literacy (AAAS, 1990a, 1993; NRC, 1996) NOS has been advocated as a critical educational outcome by various science education reform documents worldwide (e.g., Australia, Canada, South Africa, United Kingdom, United States) (Lederman, 2007) As cited in McComas et al (1998), Hurd‘s argumentation about the role of NOS (Hurd, 1960, p.34) is:

“Science is more than a collection of isolated and assorted facts… A student should learn something about the character of scientific knowledge, how it has been developed, and how it is used.”

McComas et al (McComas et al., 2002, p.3) also highlight the necessary of including NOS in science education:

“…few individuals even have an elementary understanding how the scientific enterprise operates This lack of understanding is potentially harmful, particularly in societies where citizens have a voice in science funding decisions, evaluating policy matters and weighing scientific evidence provided in legal proceedings At the foundation of many illogical decisions and unreasonable positions are misunderstandings of the character of science.”

Due to Driver et al (Driver et al., 1996), NOS has important contributions to students in 5 aspects:

- The utilitarian argument: ―An understanding of the nature of science is necessary

if people are to make sense of the science and manage the technological objects and processes they encounter in everyday life.‖ (p.16)

- The democratic argument: ―An understanding of the nature of science is

necessary if people are to make sense of socioscientific issues and participate in the decision-making process.‖ (p.18)

- The cultural argument: ―An understanding of the nature of science is necessary

in order to appreciate science as a major element of contemporary culture.‖ (p.19)

- The moral argument: ―learning about the nature of science can help develop

awareness of the nature of science, and in particular the norms of the scientific community, embodying moral commitments which are of general value‖ (p.19)

- The science learning argument: ―An understanding of the nature of science

supports successful learning of science content.‖ (p.20)

On science teaching and learning, McComas et al (McComas et al., 1998) argued that understanding NOS will: 1) enhance the learning of science content; 2) enhance understanding of science; 3) enhance interest in science; 4) enhance decision making; and 5) enhance instructional delivery It can be said that in science education, NOS is an irremovable part because, more or less, assumptions about NOS will be gradually formed by students and teachers However, NOS view of individual may be significantly divergent as teachers and students may form their own views toward science

In a socialist country like Vietnam, there are several ideas of Driver et al (Driver et al., 1996), however, seem go beyond the normal consideration of Vietnamese For example, not many citizens (including teachers and students) have appropriate opportunities to give ideas for socio-scientific issues and participate in the decision-making process As a result, they may think that it is the job of scientists, researchers, and stakeholders, not their job to care about those things Similarly, ―do student really need to understand about NOS for their own good in a convenient life?‖ will be a big question in Vietnam When Vietnamese students seem satisfy with what they already learnt from school For example, our study on constructivist learning environment in Can Tho University, Vietnam revealed that on scientific uncertainty, compare to the ―actual score‖, the ―preferred score‖ indicated just 0.29 higher in expectation (Thao-Do et al., 2014) This number is too small to suggest a need to learn more about nature of science from students However, also from this study, all the 5 teachers who were interviewed indicated very positive attitude toward constructivist learning and considered the paradigm of constructivism as an ―ideal model of learning‖ in which nature of science is an important part as in the CLES scale of Taylor and Fraser (Taylor et al., 1997) and as argued by Mathews (Matthews, 1998) that ―constructivism is at its core, as it was with Piaget, an epistemological doctrine; and it is standardly coupled with commitments to certain postpositivist, postmodernist, antirealist, and instrumentalist views about the nature of science‖ Since the early 70s until even recently, the empirical research shows repeatedly and consistently that the students and teachers do not have a proper understanding of NOS The students often hold traditional, positivist (logical empiricist), and idealistic views of science and technology, which are close to the list of myths on science (McComas, 1996), or contrary to the list of consensuses on NOS (Bartholomew, Osborne & Ratcliffe, 2004) They do not distinguish between science and technology and the current relationships among science, technology and society (STS), do not understand the role of the scientific method, theories and hypotheses, models, creativity and tentativeness in the validation of scientific knowledge (for instance, see Lederman, 2007)

Research also indicated difficulties in identifying the NOS conception and the progress in understanding of NOS as the following: