Tài liệu Constructing and using recognition problem to develop capability of detecting and solving problem, creativity capability for pupils via teaching avanced 11th organic chemistry

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MINISTRY OF EDUCATION AND TRANING HANOI NATIONAL UNIVERSITY OF EDUCATION TRAN NGOC HUY CONSTRUCTING AND USING RECOGNITION PROBLEM TO DEVELOPE DETECTING AND SOLVING PROBLEM, CREATIVITY CAPABILITY FOR PUPILS VIA TEACHING ADVANCED 11TH ORGANIC CHEMISTRY Major : Method and theory of teaching and studying chemistry subject Code : 62.14.01.11 SUMMARY OF PHD THESIS ON EDUCATION HA NOI, 2014 The thesis is completed in: HANOI NATIONAL UNIVERSITY OF EDUCATION Supervisors: 1. Ass.Prof.Dr. DANG THI OANH 2. Prof.Dr. NGUYEN HUU DINH First Opponent : Ass.Prof.Dr. Phung Quoc Viet Hung Vuong university Second Opponent : Ass.Prof.Dr. Tran Quoc Dac Educational institutes Vietnam Third Opponent : Ass.Prof.Dr. Vu Quoc Trung Ha Noi national university of education The thesis will be defended on Board of examiners at University level, meeting at: ……………………………………………………………………… at …….. o’clock, day …….., month ………, year …………… The thesis can be found in: - National Library - Library of Hanoi national university of education LIST OF RELEVANT ARTICLES AND PROJECTS OF THE AUTHOR 1. Tran Ngoc Huy, Dinh Thanh Tam (2010), Recognition problem, The V national conference proceedings of orientating innovation progam, content and teaching method – Teaching chemistry in colleges, universities, vocational training in stage from 2010 to 2020, page 230–235. 2. Tran Ngoc Huy, Dang Thi Oanh, Nguyen Huu Dinh (2011), Building some recognition problem to study new lesson in saturated hydrocarbons chapter of advanced 11th chemistry textbook. Scientific Magazine of Hanoi Pedagogical University Issue no.2, page 109-119. 3. Tran Ngoc Huy, Dang Thi Oanh (2012), Buiding some quantitative recognition problem of hydrocarbons part in advanced 11th chemistry textbook. Proceedings of scientific conferences of developing professional capacibility for chemical pedagogical students. 4. Tran Ngoc Huy, Dang Thi Oanh, Nguyen Huu Dinh (2012), Using some recognition problem of advanced 11th organic chemistry part in teaching of giving and solving problems, Applied Chemistry Magazine. 5. Tran Ngoc Huy, Dang Thi Oanh (2013), Using recognition problem in 11th grade organic chemistry to teach recognition and solution of problems. 1 INTRODUCTION 1. Reasons to select the subject Today we live in the era of information explosion, the advances of science and engineering. Education is moving from providing knowledge to develop qualities and capability of learners. Besides the advantages of current general Education Program of Vietnam, it doesn’t meet the requirements of economic development, the society in the new era. Trend of Vietnamese education innovation is to develop qualities, capability of learner, ensure harmony between "teaching of literacy" and "teach human", orientate career, focusing on promoting innovation of methods and forms of educational organizing. Recognition problem is an important solution to develop capacity, especially detecting and solving problems capacity, the creativity capacity for pupils. Coming from the above reasons, We have chosen the subject: "Constructing and using recognition problem to develop capability of detecting and solving problem, creativity capability for pupils via teaching Avanced 11th organic chemistry ". 2. Objective of research Research how to build and use recognition problem in teaching advanced 11th organic chemistry to develop detecting and solving problem capability, creativity of pupils, contribulting to innovate methods of teaching and learning chemistry at high school. 3. Tasks of research – Study the theoretical basis of cognitive theory, recognition problem in teaching chemistry at high school, developing the capacity for high school pupils, the teaching method to develop capacity for pupils. – Study the reality of using recognition problem in teaching chemistry at high school. – Study content of the organic chemistry part in Avanced 11th chemistry textbook. – Study to propose processes and build systems of recognition problem in Avanced 11th organic chemistry textbook. – Study using recognition problem in teaching methods in order to develop capability of detecting and solving problems, creative capability of pupils. – Carry out pedagogy experiments to evaluate effeciency and feasibility of recognition problem in teaching chemistry. 4. Objects and target of research 4.1 Guests can study Researching in teaching and learning chemistry in high school. 2 4.2 Research objects Recognition problem and capacity development issues in the teaching of chemistry on the pupils at high schools. 5. Scope of research Research in the organic chemistry part in avanced 11th chemistry textbook. Research in the development of capability of detecting and solving problem, creativity capability for pupils. 6. Method for research – Theory research method groups (analysis, synthesis, reasoning, modeling, expert...). – Practical research method groups (methods of investigation, observation, interviews, experimental pedagogy,...). – Mathematical method groups (mathematical statistical methods in educational science research,...). 7. Scientific hypothesis If we build a good system of recognition problem and use them effectively in teaching chemistry, teaching methods can be innovated, the quality of teaching chemistry can be improved in order to develop the capacity of detecting and solving problems, the creative capacity for pupils. 9. New contributions of the Thesis – The thesis has elucidated theoretical system of recognitive problem, has given the new concept and using recognition problem in teaching chemistry. – The thesis has proposed processes and constructed systems of recognition problem (qualitative, volume quantitative and practical form) of advanced 11th organic chemistry. – The thesis has studied fundamentials that constitute capacity, thence use recognition problem to develop capacity for pupils, especially the capability of detecting and solving problems, creativity. – The thesis has studied using of recognition problem in teaching methods to form and develope the capability of detecting and solving problems, creativity. – The thesis has researched to implement in practice. 8. Structure of the thesis Apart from introdution, conclusion, reference document, appendix and index, the content of thesis include 3 chapters : Chapter 1. The theoretical basis and practice of problem cognitive and development of capability for pupils in high school. Chapter 2. Constructing and using recognition problem to develop capability of detecting and solving problem, creativity capability for pupils via teaching Avanced 11th organic chemistry Chapter 3. Pedagogy experiments. 3 CHAPTER 1. THEORETICAL BASIS AND PRACTICE OF RECOGNITION PROBLEM AND DEVELOPMENT OF CAPACIBILITY FOR PUPILS IN HIGH SCHOOL 1.1 HISTORY OF THE RESEARCHED ISSUES – Worldwide : About the year 400 BC, Socrat built an unique teaching method is conversation – argument. It was the forerunner of the teaching method with recognition problem. Later, educational scientists such as H.J.Deway, V.Becton, Gen–tren, Vet– Jacob, Macop, M.A.Dajicob, V.Okon,... They announced the research on teaching by the questions, raise issues to make the process of teaching positive. – In Vietnam, there are a number of research works of authors such as : Nguyen Ngoc Quang, Nguyen Cuong, Dang Thi Oanh, Nguyen Xuan Truong, Tran Trung Ninh, Thai Duy Tuyen, Nguyen Cuong – Bernd Meier, Le Van Nam, the authors show the teaching method of detecting and solving problems, which relates to recognition problem to improve activeness and creativity of pupils. An overview of the history of recognition problem research, we find that however teaching ideas using recognition problem is long–standing, also initial researchs on recognition problem, nobody has studied systematically and given standard concept of recognition problem, even so applied that theory to build recognition problemof organic chemistry in high school. 1.2. COGNITIVE THEORY – THEORETICAL BASIS OF COGNITIVE PROPLEM 1.2.1 The psychological basis of cognitive theory 1.2.2 The philosophical basis of cognitive theory 1.2.2.1 The basical concepts 1.2.2.2 The nature of Cognizance according to dialectical materialism 1.2.2.3 Dialectical path of cognizance 1.3. INNOVATE TEACHING METHODS TOWARDS DEVELOPING CAPACITY FOR PUPILS 1.3.1 The concept of capacity According to Pro. Dinh Quang Bao : Capacity is defined in many different ways, can be divided into two main groups : one gets signs of psychological factors to define and the other gets signs of factors that constitute active ability to define. 1.3.2 General capacity and specific capacity of pupils 4 1.3.2.1 General capability According to Pro. Dinh Quang Bao : The general capacity includes : ownership and development itself capacity group ; Capacity of social relations group ; Capacity of tool group. 1.3.2.2 Specific capacity According to Ass.Pro Dang Thi Oanh, specific capacities in chemistry : capacity of using the chemical language, chemical practice capacity, caculating capacity, capacity of detecting and solving problems through chemistry, capacity of applying knowledge of chemistry in life, creative capacity. 1.3.3 Some characteristics of capacity There is not general capacity, capacity refers to the impact of a particular individual to a specific object for a given product. Capacity as a constituent in a particular activity. Capacity only exists in the advocacy and development process of a specific activity ; Capacity can be observed through the activities of individuals in a particular situation ; capacity exists in two forms : general and specific capability. 1.3.4 Some capacity need to be focused on developing for pupils in high school 1.3.4.1 Develope the capacity of detecting and solving problem 1.3.4.2 Develope creative capacity 1.4 SOME POSITIVE TEACHING METHODS TO DEVELOPE CAPACITY FOR PUPILS 1.4.1 Method of detecting conversations 1.4.2 Detecting and solving problems teaching 1.4.3 Visual instrument in teaching chemistry 1.4.4 Use chemiscal exercises in teaching 1.5 RECOGNITION PROBLEM 1.5.1 Exercises, problems and recognition problem 1.5.1.1 Concept of exercises. We confirm that, exercises is assigned to pupils to apply knowledge learned. 1.5.1.2 Concept of problem. We confirm that "The problem is a specific information system that contains conflicts, including the known and the unknown (which is a theory) have no explicit relationship to each other, it need to be clarified by the new scientific method. 1.5.1.3 Concept of recognition problem in teaching : Through research and analysis theory basis of recognition problem, we propose a new concept of recognition problem as follows : "Recognition problem in teaching is a identified information system, containing conflicts, including old ones and new knowledge that need to be achieved, we can only solve problem successfully by positive activities, 5 exploring, studying new solutions, meantime pupils not only acquire new knowledge but also confidence, joyfulness of a new cognitivisim”. 1.5.2 Relationship between exercises, problem and recognition problem Table 1.2 Distinction between exercises, problem and recognition problem Problem Recognition Exercises problem Purpose Scientists research, Pupils study to find Remember and find new out the new practice a skill, use knowledge, new knowledge, new a formula, a rule techniques, new skills, new solution competently. methods, formulas, methods, new relationships,... for formulas, humanity. relationships... for themselves. Feature – Contains – Contain cognitive – Not contain cognitive conflict conflict between what cognitive conflict. between the known pupils known and the and what the unknown. – Solving and the scientists have not – Solving and the result is available. found. results are not – Solving and the available for pupils results are not but available for available for science. science. Result Research to find Pupils discover new Pupils remember new knowledge, a knowledge, new knowledge, new invention, a skills, a new solution practice a skill new process method, a new fluently, a technology, new formula,… formula or a rules,... certain method of solving,... Develope Develope human Develope the capacity Not require to capacity capacity especially of detecting and develop general as detecting and solving problem, capacity which solving problem, creative capacity of essential creativity pupils. characteristics of capability. capacity. 1.5.3 Recognition problem and development of capacity for pupils Recognition problem fulfills the conditions for the formation and development capability for pupils : 6 1.5.3.1 Use recognition problem to develop the capacity of detecting and solving problems for pupils Pupils have to conduct thinking operations such as : to detect opposites that form fundamental contradiction of problem, enounce problem. Pupils give assumptions. Study to give the new process, use new skills to solve recognition problem. Thence pupils learn new knowledge, it is more important that through it to develope the capacity of detecting and solving problems for pupils. 1.5.3.2 Use recognition problem and development of ceative capacity Creative capacity is the capacity to create benefit new thing on the basis of what is already. With the prior knowledge (as raw material), we have to combine and transform that knowledge in certain conditions to find out new knowledge (new products). Through solving recognition problem, creative capacity of pupils is formed and developed, recognition problem can be considered as the important measure to form and develope the creative capacity for pupils. 1.6 THE ACTUAL STATE OF USING RECOGNITION PROBLEM IN HIGH SCHOOL IN VIET NAM 1.6.1 Planning for investigation 1.6.1.1 The purpose of the investigation Seeing the actual state of using teaching method in high schools ; Deely analysis how to teaching and learning of chemistry organization and relation with quality of teaching ; Find out the level of understanding and applying recognition problem in teaching chemistry. 1.6.1.2 Contents of investigation Investigate using of teaching method generally ; opinion of teacher about each teaching method and innovation of teaching method ; Investigate understanding specifically some teaching method through teaching practice, especially use recognition problem in teaching method to develop capacity for pupils ; Investigate specifically understanding and the using recognition problem in chemistry teaching ; Investigate the facilities that serves to teach chemistry. Advantages and disadvantages of teachers in some areas when conducting innovation of teaching method. 1.6.1.3 Location of investigation We investigated 14 high schools in nine provinces and cities are : Ha Noi (3), Bac Ninh (1), Hai Duong (1) Ninh Binh (4), Nam Dinh (1), Quang Ninh (1), Hue (1), Nghe An (1), Ca Mau (1). 7 1.6.1.4 Object of investigation The chemiscal teacher at the high school ; management staff especially specialized management in high schools, chemiscal officer in the Department of Education and Training of the province and the city. 1.6.1.5 Method of investigation, the investigation period Send and collect feedback questionnaire ; meet directly, interviewed a number of chemiscal teachers of some schools and some managers ; directly conduct class observations of some teachers ; observe directly facilities that serve to teach chemistry ; Survey period from 2009 to 2010 school year. 1.6.2 Conduct and the result of the survey 1.6.2.1 Two stage of investigation – Stage 1. Extensive investigation to orient the subject. We sent questionnaires, feedback to 94 teachers of 14 high schools. – Stage 2. We inspected knowledge and using recognition problem in teaching in high schools. Directly conducted class observations 4 lectures and converse, interview directly with the teachers, Leader, Chemiscal Expert in Ninh Binh, Hanoi, Nam Dinh, Ha Nam, Bac Ninh,... We sent questionnaires to 94 teachers of 14 hight schools. 1.6.2.2 Analyze the results of the survey Through data of the survey, we see that teachers have had a change in using new teaching method, however the traditional teaching method such as presentations, conversations are still used mainly. Understanding of recognition problem of teachers nationwide is very limited, therefore constructing and using recognition problem in teaching is very limited. Constructing and using recognition problem to develop capability of detecting and solving problem, creativity capability for pupils via teaching Avanced 11th organic chemistry. CHAPTER 2. CONSTRUCT AND USEING RECOGNITION PROBLEM TO DEVELOP CAPABILITY OF DETECTING AND SOLVING, CREATIVITY CAPABILITY FOR PUPILS VIA TEACHING ADVANCED 11TH ORGANIC CHEMISTRY 2.1. OBJECTIVES AND STRUCTURE OF CONTENTS PART PROGRAM ORGANIC CHEMISTRY GRADES 9 AND 11 To build approciate recognition problem and become problematic situations with pupils, we need to master the objectives, the content of knowledge and chemiscal skills of chemistry progam in sencondary school and content mentioned in recognition problem, especially the content of organic chemistry program in sencondary school which pupils were equipped. All that knowledge is regarded as knowledge pupils already know. At the same time teachers must 8 master the objectives, content of knowledge of organic chemistry in high school, thence the teachers identify new knowledge as it is the unknown that pupils need to explore, study and learn from recognition problem. 2.2 CONSTRUCT RECOGNITION PROBLEM IN TEACHING ADVANCED 11TH ORGANIC CHEMISTRY 2.2.1 Scientific basis of constructing recognition problem Conflict which exists in all things, the phenomenon, it is origins, dynamics of the development and cognizance, there will not be problem to be solved unless there is a conflict, thinking only operates when there is a conflict. 2.2.2 Principles of construction, process and evaluated criteria of recognition problem 2.2.2.1 Principles of constructing recognition problem a) Contain cognitive conflict, new knowledge. b) Ensure the accuracy of the content of chemical knowledge c) Ensure propriety, flexibility of recognition problem d) Promote the capacity of pupils especially capacity of detecting and solving problem, creative capacity. e) Ensure that the program's goals and skills standards 2.2.2.2 Process of constructing recognition problem Step 1. Identify the knowledge that pupils have known and knowledge required to form. Step 2. Construct basic cognitive conflict, that is possible for pupils to solve. Step 3. Construct recognition problem : Select the initial data (from the knowledge students already know, from the photographs, paintings, experiments from textbook) in accordance with the level of pupils to create cognitive conflicts with (the unknown) requirements of recognition problem. Step 4. Verify the accuracy and science, according to the criteria of recognition problem. 2.2.2.3 Evaluated criteria of recognition problem: recognition problem must ensure the following criterias : Contains conflicting perceptions ; Contains new knowledge ; Ensure objectives, programs, standards of knowledge, skill ; The structure consists of three parts: the known, the unknown and allow solution ; Absorbing medium strength, cognitive ability and resolve of HS; The language must be clear and bright. 2.2.3 Construction many forms recognition problem part of advanced 11TH organic chemistry 2.2.3.1 Construction the feature of the problem a) Qualitative recognition problem 9 RP 2. Construct recognition problem of halogenated alkanes substitute reaction Step 1. Knowledge that pupils have known and knowledge required to form → CH3–Cl + HCl – Knowledge pupils have already known : CH4 + Cl2 ⎯as⎯ th Pupils have already known this reaction in class 9 ; Tier carbon ; activity levels of the halogen. – Knowledge is required to form : Reaction in which hydrogen in alkanes is replacing gradually the H atoms by halogen atoms (Cl, Br), substitute reactions of saturated hydrocarbon with halogen is disruption σ (C–H) bond and Cl–Cl bond to form σ (C–Hal) bond and H–Cl bond ; factors affecting the products of displacement reaction. Step 2. Construct basic cognitive conflict In 9th class, pupils have already known : CH4 + Cl2 only get CH3Cl, but observing drawings 5.4 in 11th chemistry textbook, they see 4 organic products. Conflicts 1. + From the equation: as (1:1) CH3 − CH2 − CH3 + Cl2 ⎯⎯⎯ → CH3 − CHCl − CH3 + CH3 − CH 2 − CH 2 Cl + HCl 2 − clopropan (57%) 1 − clopropan (43%) There are six H –C(I) and only two H–C(II) in propane, but when it reacts with chlorine, the products that replace H–C(II) are more than the products that replace H–C(I) ? Conflict 2. o t (1:1) CH 3 − CH 2 − CH 3 + Br2 ⎯⎯⎯ → CH 3 − CHBr − CH 3 + CH 3 − CH 2 − CH 2 Br + HBr 97% 3% Why chlorine replaces both H–C(I) and H–C(II) but bromine only prioritizes to replace H–C(II). Conflict 3. Step 3. Construct recognition problem – Observe the drawing 4.5 in advanced 11 th Chemistry Textbook : What products do we obtain when CH4 reacts with Cl2 ? Why do we obtain those products ? Discovered the concept of H in alkanes substitute react. – Compare the number of H–C(I) and H–C(II) in the molecule CH3–CH2–CH3 and predict how many product do we get if CH3 – CH2 – CH3 reacts with Cl2 (as, 1:1) ? Which are main products, byproducts ? Write chemiscal equation. Which is main products, byproducts in textbook ? Why ? Make conclusion about replaced possibility of H at different levels of carbon in alkanes. – Write structural formula of products of the following reactions: t o (1:1) → (2) CH3 − CH 2 − CH3 + Br2 ⎯⎯⎯ What proportion of main products, byproducts ? Comparison rate main products, byproducts in the (1) and (2) reaction, from that, what do you find 10 out ? Explain and make conclusion about new knowlage of the alkanes substitute react. Step 4. Check againt Recognition problem make sure the accuracy and science, according to the criteria of recognition problem. b) Quantitative recognition problem RP 4. Determine volume of CO2 and H2O from combustion products. Step 1. Knowledge that pupils have known and knowledge required to form Known knowledge : The way to change organic compound into inorganic compound is simply combustion reaction ; Concentrated H2SO4 is absorbing ; CO2 react with solution Ca(OH)2. Knowledge needs to be formed : Various processes to find the volume of CO2 and H2O from combustion products of organic compound. Step 2. Identify cognitive conflict : Only with two pitchers of solution Ca(OH)2 and concentrated H2SO4, sufficient laboratory equipment and experimental conditions, Which ways to determine the volume of CO2 and H2O ? Conflict ! If there are not solution Ca(OH)2 and concentrated H2SO4 in the laboratory, what may be replaced ? Step 3. Construct recognition problem To quantify CO2 and H2O when completely burn 8.6 grams C6H14, people prepared Ca(OH)2 và concentrated H2SO4 and full laboratory equipment. a) Construct various processes (steps) to determine the volume of CO2 and H2O. b) If there are not solution Ca(OH)2 and concentrated H2SO4 in the laboratory, what may be replaced ? 2.2.3.2 Construct on the level of cognitive We construct recognition problem on four levels : Knowledge ; Understanding ; Applying ; Creative applying RP 8. Hydrogen bonding Step 1. Knowledge that pupils have known and knowledge required to form – Known knowledge : Boiling temperatue depends mainly on the mass number (M) of the compound ; nature of the chemical bonds are due to electrostatic forces of oppositely charged particles. – The knowledge need to be formed : The degree to know : There is hydrogen bonding between the alcohol molecules, It make raises the boiling temperature of the alcohol than the equivalent of M but there is no hydrogen bonding. The level of understanding : The nature of the hydrogen bond formation between the alcohol molecules, thereby generalize to the formation of hydrogen on the link between alcohol molecules. 11 Level of applying : To apply the adhesive to explain the hydrogen bond formation in some cases hydrogen with electronegative elements such as F, O, N, S, ... to explain the temperature boiling of the pair : H2O and C2H5OH ; H2O and H2S ; HF and HCl ; HCHO and CH3OH ; ... The level of creative application : Applying the hydrogen–bonding nature to solve the unusual case of experimental and practical, such as Na reaction with HF ; especially the solid and liquid water , ... Step 2. Identify cognitive conflict a) Level of Knowledge: substances CH3OH, CH3CH3 v CH3F have nearly equal M, the boiling temperature are about equal, but CH3OH (ts = 65) has significantly higher boiling temperatue than substances such as CH3CH3 (ts = –89) ; CH3F (ts = –78). What factors cause this phenomenon ! Conflict! b) Level of understanding : When two CH3OH molecules closer together, O atom has ability to close two H atoms (Figure 1, 2), but in fact there is only one case of hydrogen bond formation. Conflict. O−H H 3C (1) O−H H 3C H HOH 2 C O−H H 3C (2) C. Level of applying: Why is molecular weight of H2O (M=18) smaller molecular weight of C2H5OH (M = 46) but boiling temperatue t s (H2 O) = 100 o C higher boiling temperatue t s (C2 H5OH) = 78,3o C . Conflict! – O and S in the same group, chemical formula H2S (M = 43) and H2O (M = 18) but at normal temperature H2S gas is still liquid H2O ? .... d) Level of creative applying: When drop Na in HF solution, reaction product is usually NaF but reaction product is mixture of NaF and NaHF2. Conflict! Step 3. Construc recognition problem a) Table 8.4 (advanced 11th Chemistry textbook) : CH3CH3 CH3OH CH3F M (g/mol) 30 32 34 o ts ( C) –89 65 –78 Indicate what factors have influenced this anomaly ? What’s new knowledge from that ? b) Between two CH3OH molecules, there‘re two ability to close H and O as follows : O−H H 3C (1) H 3C O−H H HOH 2 C H 3C (2) O−H 12 Which circumstance forms hydrogen bonds ? Why ? Give concept of hydrogen bonds and conditions to form hydrogen bonds? o c) Why H2O (M = 18) < C2H5OH (M = 46) but t s(H2O) = 100o C > ts(C2H5OH) = 78,3 C ? – H2S (M = 43) and H2O (M = 18), Which boiling temperatue of moleculers is higher ? Look up to find documents about boiling temperatue of two substances and explain what causes it. Draw conclusions. d) – Give Na reacts with liquid HF obtained what product ? Why get these products ? What knowledge drawn from which ? – You know, my puzzle of what Hot is shrinking, it's cold out? Explain this anomaly and knowledge learned something new. 2.2.3.3 Construct recognition problem content of which relates to experiments and applying chemistry knowledge in practice We find that, exercises in textbook is difficult to implement construction of recognition problem for pupils to find new knowledge when conducting experiment, because pupils have already known to solve cognitive conflict. Recognition problem can not aim at forming a new skill for pupils, because experimenting in textbooks is made clearly. So how do have to be constructed ? it’s a recognition problem ! RP 12. Application of acetylene as fuel Step 1. Knowledge that pupils have known and knowledge required to form – Known knowledge : The reactions of burning hydrocarbon release much heat ; Write chemical equation of the combustion reactions. – Knowledge required form : with same volume of alkanes, alkenes, alkyl (same number of carbon atoms), the combustion temperature of alkyl is the highest fire. Therefore, C2H2 is used in industrial soldering. Step 2. Identify cognitive conflict Burn the same amount of each gas C2H2, C2H4, C2H6 by the air, the combustion temperature of C2H2 is the smallest, but why do people only use C2H2 in industrial soldering without two the others in fact ? Step 3. Construct recognition problem Burn the same amount of each gas C2H2, C2H4, C2H6 by the air, combustion temperature of C2H6 (341.260cal/mol) ; C2H4 (316.200cal/mol) and C2H2 (300,000 cal/mol). Which gas is used to be fuel in industrial soldering ? Why ? 2.2.4 System of recognition problem in advanced 11th organic chemistry 2.2.4.1 Construct some qualitative recognition problem 2.2.4.2 Construct some volume quatitative recognition problem 2.3 USE RECOGNITION PROBLEM IN TEACHING CHEMISTRY 13 2.3.1 Use recognition problem to develop some capacity of pupils in high school Recognition problem contain full of elements to develop capacity of pupils because they are structured by three components as : conditions, requirements and solutions, the conditions often conflict with requirements and not available solutions, this special structure contains new knowledge, new skills, new methods, and this structure also help pupils to reveal and develop their capacity, especially capacity of detecting and solving problems, creative capacity. 2.3.1.1 Principles and requirements when using recognition problem system to develop the capacity of pupils in high school a) Principles of using recognition problem system to develop capacity of pupils Principle 1. Ensure to implement general education objectives of chemistry. Principle 2. Ensure that to transfer conflict of recognition problem into internal conflict of pupils successfully. Principle 3. Note to exploit the paticular of chemistry. Principle 4. Ensure the quality time of teaching. b) Requirements of using recognition problem to develop capacity of pupils – The recognition problem used in teaching must be accurate, and it has to emerge knowledge formed for pupils. – The recognition problem used in teaching must be consistent with the level of pupils – Using recognition problem has to ensure the time of teaching. – Select suitable method of teaching to reveal role of recognition problem in the development of particular capacity of pupils. 2.3.1.2 General procedure of using recognition problem system to develop pupils' capacity in teaching chemistry a) The general procedure used recognition problem system 1. Plan to develop pupils’ capacity through the system of recognition problem. 2. Select the method of teaching to reveal the characteristics of recognition problem best, facilitate for the formation and development of pupils' capacity. 3. Evaluate the effectiveness and limitations of recognition problem in forming and developing each of pupils' capacity, then adjusting, orienting approciately to promote the advantages and restrict disadvantages. The process of using a recognition problem to develop the pupils’capacity Step 1. Detect problems through detecting conflict and pedagogical transformation – Let pupils study recognition problem and detect cognitive conflict. – Perform pedagogical transformation, teachers use method of teaching, appropriate pedagogical skills to transform conflict of recognition problem into problematic situations of pupils so that pupils speak out the problem to be solved. 14 Step 2. Solve problem : pupils think to propose possible hypotheses, and then excluding, retaining only viable hypothesis ; For each hypothesis, pupils establish procedures and solve. Step 3. Make conclusion and draw out new knowledge : New knowledge drawn out ; New method to find that knowledge, new skills were made during solving. 2.3.2 Use recognition problem to develop the capacity of detecting and solving problems – To know how recognition problem affect development of capacity of detecting and resolving problems of pupils, teachers need to master the signs of this capacity. – Select recognition problem that have clearer cognitive conflict to use in teaching, in order to promote detecting and solving problems capacity. For example. Recognition problem of halogenated alkanes reaction. – Observe the shape 5.4 in advanced 11th chemistry textbook we see that: what products are obtained when CH4 react with Cl2? Why ? Draw out the nature of replaced reaction of H in alkanes. – Compare the number of hydrogen atoms at Carbon level 1, Carbon level 2 and H in the molecule CH3–CH2–CH3 and predict if CH3–CH2–CH3 reacts with Cl2 (1:1), how many products do we get ? Which products are main products, byproducts ? Write chemical equation. In fact (according textbook) Which products are main products, byproducts? Explain the causes and conclude about the replaced possibility of H at different level carbon in alkanes. – Write products of the following each reactions : t o (1:1) CH3 − CH2 − CH3 + Br2 ⎯⎯⎯ → What proportion of main products, byproducts in each case ? Comment and conclude about replaced ability of the halogen. Step 1. Let pupils study recognition problem to find cognitive conflict and teachers implement pedagogical metabolism so that pupils enounce studying problems. In 9th class pupils knew CH4 + Cl2 only obtain CH3Cl but observing shape 5.4 in advanced 11th chemistry textbook we see 4 organic products. + From the equation: as (1:1) CH3 − CH2 − CH3 + Cl2 ⎯⎯⎯ → CH3 − CHCl − CH3 + CH3 − CH2 − CH2Cl + HCl 2 − clopropan (57%) 1 − clopropan (43%) 15 There are 6H at the carbon level 1 in propane, while there are only 2H at carbon level 2, when those H react with Cl, products that replace H at Carbon level 2 are more, than products that replace H at Carbon level 1. Conflict. o t (1:1) CH3 − CH2 − CH3 + Br2 ⎯⎯⎯ → CH3 − CHBr − CH3 + CH3 − CH2 − CH2Br + HBr 97% 3% Chlorine and bromine are both halogen but when insteading Cl2 by Br2 in replacement reaction What causes that led to such a great byproduct ? Step 2. Solving problems With every conflict pupils can propose hypothesis, however teachers help pupils choose appropriate hypothesis to establish process of solving. + With the first conflict, teachers orientate pupils to choose close hypothesis and necessarily hypothesis is that 4 H in CH4 in turn be replaced by H. + With the second conflict, teachers should orientate pupils to compare the number of H in C (I) and H in C (II) and the response capability of Cl2 and Br2 to understand the rate of main products, byproducts. + With the third conflict, When pupils have solved the second conflict, the teachers orientate pupils to focus on intensity of Cl2 and Br2 when they participate reaction. Step 3. Make conclusions and draw out new knowledge Replacement reaction is the reaction in which atoms (Cl or Br) will gradually replace the H atoms in the alkane to create the product. The repalcement possibility that H–C(I) < H–C(II) < H–C(III) and Cl2>Br2. 2.3.3 Use recognition problem to develop creative capacity for pupils – To develop creative capacity for pupils through recognition problem then need to determine the signs of this capacity. – When study depth of recognition problem and the creative capacity we show that the nature of the process of detecting and establishing procedures to resolve conflicts in recognition problem is scientific cognitive cycle as a creative process by VG Razumovsky proposed. Example 1. Quantification of CO2 and H2O To quantify CO2 and H2O when complete burn 8,6 g C6H14, we prepare the chemistry Ca(OH)2 and concentrated H2SO4 and full laboratory instruments. How many ways do we determine the volume of CO2 and H2O when conducting the experiments ? Build process of counting CO2 and H2O for each way. Step 1. Let pupils study recognition problem to detect cognitive conflict When complete burning 8,6 g C6H14 escaping gas mixture is CO2 and H2O, which ways may we have to quantify them ? Which pot do we let this 16 mixture passes before ? If the mixture is passed through only solution Ca(OH)2 without H2SO4, do we quantify ?.... For each way how to determine the volume of each of CO2 and H2O ? Depend on the ability and reasoning ability of pupils who will have many ways of quantification, through which the creative expression of pupils will be revealed. Step 2. Pupils propose different solutions depending on the creativity of each pupils : Method 1 : Due to the characteristics of concentrated H2SO4 is absorbing, Ca(OH)2 absorb CO2, so that we turn the mixture over H2SO4 solution, then Ca (OH)2 solution. The increase of the volume of H2SO4 pot is the volume of H2O. The increase of the volume of Ca(OH)2 pot is the volume of CO2. Method 2 : Let mixture pass through residual Ca(OH)2 solution, both H2O and CO2 are trapped in the pot. The increase of the volume of Ca(OH)2 pot is the volume of CO2 and H2O.CO2 reacts with residual Ca(OH)2 generating precipitated CaCO3, when we determine the volume of CaCO3,we will determine the volume of CO2 and infer volume of H2O. Method 3 : When absorbing H2O, concentration of H2SO4 can be diluted, so that determine the percent concentration of H2SO4 before and after absorbing water, remaining gas CO2 is put into solution of Ca(OH)2. Method 4. Pupils can infer other ways creatively. Step 3. Make conclusions: Pupils wil draw out process of determining CO2 and H2O to identify molecular formula later. This recognition problem contains sufficient elements to promote creative ability. 2.3.4 Use recognition problem in accordance with purposes of teaching We use recognition problem in conversation detection method, complex method of detecting and solving problem, the angle based teaching method and orientate teaching purposes in schools such as : Teach pupils to study new lesson ; Complete knowledge, skills (review, exercise, practice, experimentation) assess pupils. Through research theory and teaching practice, we propose process of using recognition problem according to teaching purposes as follows : Step 1. Detect problems through finding cognitive conflict and implement pedagogical metabolism a) With the pupils, pupils detect problems through finding conflict b) With teachers, teachers perform pedagogical metabolism Step 2. Solving problem Step 3. Draw out conclusion, new knowledge and apply new knowledge. 2.3.4.1 Use recognition problem in new lesson studing format a) Characteristics of the recognition problem when studying new lesson b) Use recognition problem to form new knowledge 17 Example 1. Hydrogen bonding Step 1. Detect problems from detecting the conflict in recognition problem: a) Observe table 8.4 (advanced 11th chemistry textbook) and what do you comment about boiling temperature of substances ? What causes such a difference ? CH3CH3 CH3OH CH3F M (g/mol) 30 32 34 o ts ( C) –89 65 –78 Draw out conclusion about the hydrogen bonds. b) Applying the theory, explain the following cases : H2O has ts(H2O) = 1000C while C2H5OH has only ts(C2H5OH)=78,30C? Teachers perform pedagogical metabolism (conflict transformation). a) The substances have nearly equal M, boiling temperature of them usually are nearly equal, but why is boiling temperature of CH3OH (ts= 65) much higher than the substabces such as CH3CH3 (ts= –89); CH3F(ts= –78) have equal M with it ? So that, besides M, What elements do boiling temperature of substances upon on ? b) H2O (M = 18) < C2H5OH (M = 46), H2O and C2H5OH have both hydrogen bonds but t s (H2O) = 100o C > t s (C2 H5OH) = 78,3o C ? Step 2. Solving problem Pupils can give different hypothesis, teachers should discuss and guide pupils to keep hypothesis that can solve conflict. a) We predict that there are at least three hypothesis about the bond between CH3OH molecules arising in the process of inference of pupils, they are: – Between CH3OH molecules can form covalent bond. – Between CH3OH molecules can form ionic bond ? – Or Is there any new bond. Pupils conduct to give process of resolution: When analysing structure of two molecules CH3OH, pupils observe that there are a kind of atom O and two kinds of atom H, so happening the two possibilities that H and O are close together (as drawing a, b) : O−H H 3C (1) H3C O−H H HOH 2 C O−H H 3C (2) When comparing electronegativity between atoms, pupils will find that forming type b bond is not possible. Bond between Hδ+ of group OH of this
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