Tqp chi khoa hQc Triing Dqi hgc Quy Nhcfii Sd''''3, Tqp VII ndm 2013 BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFFICIENCY OF TEACHING AND LEARNING CHEMISTRY FOR HIGH SCHOOL GIFTED STUDENTS[.]
Tqp chi khoa hQc Triing Dqi hgc Quy Nhcfii - Sd'3, Tqp VII ndm 2013 BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFFICIENCY OF TEACHING AND LEARNING CHEMISTRY FOR HIGH-SCHOOL GIFTED STUDENTS NGOTHINGOCMAP INTRODUCTION Chemistry not only plays an important role in the life and production but also has an important implication for the national economy, in construction and defense Chemistry is an experimental subject because chemical knowledge is much applied in real life Therefore, it can enable students have deep understanding of the outside world if the teacher exploits as many situations in teaching as possible, especially through building up and handling the systems of chemical practical exercises Chemical practical exercises help students understand knowledge, expand knowledge, cultivate critical thinking, patience, and use prior knowledge to solve the problems which arise in real hfe CPE used in chemistry teaching promotes students' positive attitude, inspires their love of chemistry However, nowadays in the curriculum set by Ministry of Education and Training, most chemical exercises, including professional and amateur programs, are often far from real life and production This results in students' boredom and makes it harder for them to obtain knowledge The theory-attached teaching leads to limited creative thinking and appUcation abihties of Vietnamese students, especially gifted ones, in comparison with international counterparts Therefore, building and using CPE systems lo establish and consolidate their knowledge of chemistry as well as fostering the ihinking ability is getting essential BUILDING PRACTICAL EXERCISES IN TEACHING AND LEARNING CHEMISTRY 2.1 Concept and effects of CPE in teaching and learning chemistry Chemical practical exercises are the chemical exercises which have contents associated with real life, and require studenls to use chemical knowledge to solve the problems posed by practice such as explaining natural phenomena, interpreting habits of living and labor, environmental conservation, analyzing production process, experimental methods CPE can be classified differently If they are based on the level of requirements, CPE can be divided into types: qualitative and quantitative exercises If based on the NGO THI NGOC MAI- 34 knowledge aspects, they can be divided into environmental CPE, life CPE, and chemical manufacturing CPE CPEs used in teaching and learning chemistry not only have effects on doing general chemical exercises, but also have the following effects on: - Training and developing studying skills: gathering information, applying basic knowledge to handle the situations, selecting knowledge to solve practical problems - Training and developing thinking skills: analysis, synthesis, comparison, - Training ability to use knowledge of chemistry to detect and resolve the problem posed by the practice, thereby expanding understanding and knowledge and contributing to improving the quality of life - Helping students understand about natural resources, environment, human activities in life and production, and hot global issues - Making conditions for studenls to use multiple senses, promote positive, selfactive and creative attitude in the learning process Helping studenls Hve more responsibly for family, community and society Taking moral education; training accuracy, patience; stimulating interest, curiosity, passion in science and technology research 2.2 Principles of building CPE [3] - Ensure the accuracy, science and modernity In a chemical practical exercise, besides certain chemical contenl, there are real data that need to be put in correctly but nol arbitrarily changed with the purpose of easy computation In some exercises of chemical production, we should provide the technological lines being used in Vietnam or in the world, and avoid presenting the technology which is too old or outdated and is not used or rarely used - Be close to students' experiences The practical issues related to chemical knowledge are very abundant If CPE have contents close to students' experiences, lives and surrounding habitats, they will motivate and attract students when receiving and solving problems - Be close to the learning content Practical exercises should have contents that are close to the syllabus that students are following If practical exercises with entirely new contents on chemical knowledge, they will discourage students from working out the answers to the problems - Make sure of the pedagogy Practical situations are more complex than the chemical knowledge in the high BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFFICIENCY 35 school syllabus; as a result, to build practical exercises for high school students, it is necessary to have a pedagogical process to simphfy practical situations The request for the practical exercises must be also appropriate to students' level - Be systematic and logical The practical exercises in the teaching's program should be arranged in chapters, articles, lessons and the level of the student's development, In each chapter, each lesson there should be all types, all kinds of practical exercises In the teaching process, through inspection, evaluation, we need to build practical exercises moderately and slightly higher than the level of awareness of students to gradually increase the level, the acquisition of knowledge We should transform the content of practical exercises in the form of access to modules Build up a number of typical exercises which can assemble into specifically practical situations, the specific content of the unit, or turn a complex problem to a simpler one, create new exercises 2.3 The process of building CPE To build chemical practical exercises which are appropriate to the level of awareness and life experiences of both students and inculcate their knowledge is not simply The CPE must be scientifically accurate, keep abreast with high school programs, close to manufacturing and life, inspirit confidence and passion for science In the process of building CPE, we applied the following steps: Step Preparation - Analyze the target of the chapter and the lesson to guide the design exercises - Carefully study the content of textbooks, references about chemical content and applications of chemical substances in practice; learn the lechnology of manufacture related to chemical contents of the lesson - Do research on the characteristics, cognitive abilities, hfe experiences of students lo design appropriately practical exercises and create excitement for students when solving exercises Step 2: Building CPE - Design CPE accordance with the requirements in step - Solve and verify the practical exercises - Preconceive the solutions of each exercise, the solutions from studenls, the susceptible mistakes of students during the process and provide a fix Step 3: Application - Consult with experts and colleagues NGO THI NGOC MAI- Correct the defect, unreasonable content and add the lacking details - Foresee the time and methods used to achieve the highest efficiency USING PRACTICAL EXERCISES IN TEACHING AND LEARNING CHEMISTRY Increasingly use CPE as methods and means to build, strengthen and improve the knowledge and skills of students in teaching chemistry They will promote positive, self-active learning to students, help students acquire knowledge more easily, practically and closely CPE should be used more often in both theoretical and practical teaching, in all forms of lest (oral test, multiple-choice tests, writing test, etc.), and in training chemistry for gifted students to improve results and practical implications of teaching and leaming chemistry in high school 3.1 Using CPE in teaching and learning chemistry [2] CPE can be used in all steps of the teaching process In accordance with the specific content of each unit and each chapter teachers can choose the time and mode to use CPE appropriately to achieve the highest efficiency - Designing situations leading to the new knowledge Example: Unit 31 - Chemistry 10 - Advanced program Teacher gives a question: There is an acid helping to digest food in our stomachs What is that acid? Student answers: Hydrochloric acid Teacher poses the problem: Low concentration of HCI in the stomach helps digestion process occur more easily So what are characteristics, properties and applications of HCI like Lesson 31 will help us find out the solution of those problems (Hydrogen chloride - hydrochloric acid) - Forming new knowledge Example: Unit 44 Hydrogen sulfide - Chemistry 10 - Advanced program After completing Section II - Physical properties, teacher can use the following CPE: When dissolving a small amount of hydrogen sulfide into water, we get a colorless solution Put this solution in the air for several days, then the solution is turbid Explain and write the chemical equations When solving this exercise, students receive new knowledge lightly: when 0^, known as strong oxidant, oxidize H,S to form the substances containing water-insoluble elemental S at higher oxidation state, that is sulfur So H^S is a reductant Through this exercise, students also develop the thinking skills such as judgment, analysis BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFHCIENC Y 37 - Applying knowledge and application Example: Unit 32 - Chlorine compound containing oxygen [1] When teaching Section II - Javel water, calcium oxychloride, potassium chlorate, and teachers can use the following CPE: Explain why Javel waler can bleach fabrics and why people actually use calcium oxychloride more than Javel water? Instructions: In Javel waler, CIO" is strong oxidizing agent because chlorine that has oxidation number of +1 can gam electron easily to form Cl', so it oxidizes colored substance into colorless substance Calcium oxychloride reacts with CO^, in the ak, and releases HCIO, so it has similar applications to Javel water : 2CaOCl, + CO, + H^O -^ CaCO^ + CaCl, + 2HC10 Calcium oxychloride is also used for bleaching textiles, paper, disinfectant landfills, sewage, treatment of toxic organics Large amount of calcium oxychloride is used to refine petroleum Compare wilh Javel water, calcium oxychloride is cheaper, higher percentage of hypochlorite, easier storage and transport, so it is used more commonly -> This exercise helps students understand the chemical properties of Javel water and calcium oxychloride that are the strong oxidants Thanks to it, students can get knowledge deeply and practice chemical thinking better - To consolidate knowledge and practice Example: Unit 36 - Iodine Potassium iodide is mixed with table salt to form iodine salt that is a substance oxidized to I^ and evaporated easily, especially in the presence of water or other oxidizing agent in salt, or when at high temperatures According to the research, after months KI in salt will disappear completely To overcome this, we limit the water content of iodine salt that does not exceed 3.5% in mass (by former Soviet standards) by adding stabilizers to iodine such as Na^S^O^, which can be kept KI in iodine salt for about months a Calculate the maximum amount of water containing in a ton of iodine salt by this standard b Indicate method of preserving iodine salt and use iodine salt when it is used in cooking to limit iodine escaping NGO THI NGOC MAIIodised salt is table salt mixed with a minute amount of various salts of the element iodine The ingestion of iodide prevents iodine deficiency But for a times, at normal teinperalure, on the light Iodised salt were decomposited by the reactions: Kl + H , + O, ^ K H + I^J -I- K|I(I),1 and KI -I- CO, -1- O, -> KjCO, i- I^ The NajS,0, make to reduce the decomposition of iodised salt: N a , S , , -^ IJ ^ Na.S.Oj + 2NaI a The maximum amount of water containing in a ton of iodine salt is 10^.3.5% = 3.5.10'(g) b Preserve iodine sah in a cool place, away from moisture, avoid direct sunhght and high temperatures When we cook, iodine salt is only used after the food has been cooked —> This exercise helps students inculcate the knowledge, connect the knowledge in the textbook with the life and production Exercise is not only trained calculating skills but also know how to preserve and use iodine salt properly in order to prevent goiter - Make use of CPE during experiments To take advantage of practice time, teachers should assign CPE for students to prepare at home The CPE must be based on targets, tasks, content of the lesson and students' ability - Use iu outside activities of class time In extracurricular activities, besides students themseh es perform fun expenments, the teacher can give students some practical exercises to help them apply chemical knowledge learned into life, thereby evoke passion science in generally and chemistry in particularly For example: At first the teacher can give CPEs to indi\ iduals groups or a class o r e v e n several classes, then ask them to collect, analyze and process information At the end of extracurricular, the teacher gives more CPEs and require to students to write a report and have realistic plans 3.2 Use CPE to foster gifted students Practical exercises not only are worked actively in the process of teaching and learning general chemistry program but also improve the efficiency and quaUty of training chemitry to gifted students both in theory and practice If the CPEs apphed in amateur programs are usually simple or very general qualitative and quantitative exercises, the CPE used in teaching professional program BUILDING UP AND USING PRACTIC/VL EXERCISES TO ENHANCE THE EFFICIENCY 39 and fostering gifted students are more complex and more detailed excercises relating to the phenomena of life, production processes All force students to have deeper chemical knowledge and higher ihinking skills CPEs are used in professional program and training gifted students al all levels mainly classified according to knowledge areas such as general chemistry, inorganic chemistry, organic chemistry, analytical chemistry, Example: Using three steps of the process of building CPE (1.3), we built the exercise below: Niacin (also known as vitamin B,, nicotinic acid and vitamin PP) is an organic wilh the formula C^^H^NO, and it is one of five vitamins (when lacking in human diet) associated with a pandemic deficiency disease: niacin deficiency (pellagra), vitamin C (scurvy), thiamin deficiency (beriberi), vitamin D deficiency (rickets and o s t e o m a l a c i a ) , vitamin A deficiency (night blindness and other symptoms) One recommended daily allowance of niacin is 2-12 mg/day for children, 14 mg/day for women, 16 mg/day for men, and 18 mg/day for pregnant or breastfeeding women[5] The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan lo make one mg of niacin Several million kilograms of niacin a r e m a n u f a c t u r e d e a c h y e a r , starting from 3methylpyridine u 3-Methylpyridine is produced industrially by the reaction of acrolein with ammonia or acrolein, propionaldehyde, and ammonia Write the reactions b Write structural fomular of L-Tryptophan or (2S)-2-amino-3-(lH-indol-3-yl) propanoic acid, Niacin or pyridine-3-carboxyhc acid and 3-methylpyridine V- Caculate the 3-methylpyridine need to manufacture niacin for one million people in one year Assume a person average need 15 mg niacin a day and the overall percentage yield of this synthesis is 80% Instructions: a 3-Methylpyridine is produced industrially by the reaction of acrolein wilh ammonia: CHjCHCHO-H NH3 -^ S-CHjCjH^N + H , This reaction is nonselective and a more efficient route start sacrolein, propionaldehyde, and ammonia: CHXHCHO + C R C H , C H O + N R -> 3-CH,C,H,N + R O + H, NGO THI NGOC MAI' b Structural fomular: O L- Tryptophan ian Niacin 3-methylpyridiiie O OH 93 (g) ^i=!5!L^ 123 (g) The mass of niacin for one miUion people in one year: IO*" 15.10"^.365 = 5,475.10* (g) = 5,475 (tons) 5,475.93 IOO The mass of 3-methvlpyridine = — — — ^ = 5,1745 (tons) —> This exercise requires students to master good knowledge about the reaction mechanism, stereochemistry, characteristics of functional groups, scientific calculation, so they can have an insight into knowledge and practice their thinkirtg abilities Moreover, it helps gifted students to apply chemical knowledge, especially specialized knowledge, on solving practical problems, which not only learn more about the production process but also improve confidence in science, the love and passion in research as well EDUCATIONAL EXPERIMENT To evaluate the feasibility and effectiveness of the building and using CPE systems in teaching chemistry in high schools, we have conducted experiments at Le Quy Don speciahzed high School - Binh Dinh We have chosen two advanced classes which have equal levels They are llAl_Experiment class (Exp_class, 45 students) and lIA2_Control class (Con_class, 45 students) We have had them take an input test, then proceed to teach two new chapters: nittogen and carbon, with using CPE systerms in Exp^class and traditional lesson plan in Con_class Both two classes are taught by Ngo Thi Ngoc Mai, teachers, teaching the same content and giving the same tests When finishing the program, we conducted a 45-minute multiple choice test The experimental results are as follow: [4] BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFFICIENCY Table Results of tests Test Mark X, Object Exp Input 10 0 0 11 12 0 0 4 13 II 0 0 0 12 10 0 0 12 12 (45) Con (45) Exp Output (45) Con (45) Table Classification of learning outcomes of students ( % ) Poor (marks 0-4) Average (marks 5, 6) Exp (45) 6.67 Con (45) 8.89 Exp (45) Con (45) ^^^^- ^^ Class Input Output Fair (marks 7, 8) Good (marks 9, 10) 31.11 51.11 11.11 24.45 53.33 13.33 0.00 24.44 48.89 26.67 6.67 28.89 53.33 11.11 Table The sum of the statistical parameters statistical parameters Input Output X Exp(45) 6.89 Con (45) 691 Exp (45) 7.51 Con (45) 6.89 'sB P 0.986 0.942 0.967 0.033 On the basis of experimental results, we can conclude: - There was a significant difference in marks between two classes when they are tested input and output Average marks of output test of Exp_class are always higher than Con_class Percentage (%) of students that get poor and average marks of Con_class are always higher than Exp_class The percentage (%) students that get fair and good marks in Exp_class are always higher than Con_class This demonstrates NGOTHI NGOC MAI* that using CPE systems has effected to improve quality teaching and leaming chemistry in high school - Comparing r^^ and p values between input and output test, we realize that using CPE has great influence on the ability of receiving knowledge and thinking of students - Comparing students' altitude toward learning in the teaching hours used CPE, we find oul that students in Exp_class always have more positive and passional attitudes toward learning CONCLUSION Chemistry has characterized experimental science and applications, so building and developing a system of practical exercise perfectly and suitably for students' capacity is in fact vital to apply them regularly in teaching and leaming chemistry Based on the principles and building processes of CPE, we have selected and built a syslem of exercises with more than 500 appropriate CPE which can be applied to the lessons of advanced chemistry 11 and more than 100 CPE used for training gifted students at all levels These are mainly taken from the references from the foreign or international examinations and documents Having conducted the experiment m two advanced class 11 at Le Quy Don speciahzed high School - Binh Dinh, the results of pedagogical experiment demonstrate that the system of CPE was well-selected, which improved students' abihty of acquiring chemical knowledge and their development of critical thinking REFERENCES [1] N X Truong, Chemistry wilh real life Episode 1, Hanoi National University Publishing House (in Vietnamese) (2009) [2] N Cuong, N M Dung, N T Suu, Chemical teaching methods Education Pubhshing House (in Vietnamese), (2000) [3] D C My, Construction, selection system of theoretical questions and practical exercises Master thesis of Science education, Hanoi University of Education (in Vietnamese), (2005) [4] Project of Vietnam - Belgium Applied scientific pedagogical research, Hanoi University of Education Publishing House (in Vietnamese), (2010) [5] Jacobson E L., Niacin, Linus Pauling Institute, (2007) BUILDING UP AND USING PRACTICAL EXERCISES TO ENHANCE THE EFFICIENCY ^ XAY D U N G VA SLf DUNG BAI TAP T H U C TIEN NHAM NANG CAO HIEU QUA DAY HOC VA BOI D U G N G HOC SINH GIOI HOA HOC CJ TRUCJNG TRUNG HOC P H T H N G Ngo Thi Ngoc Mai Bai tap hda hpc c6 npi dung gin vdi thiTc tien (BTTT) \k nhO'ng bki tap van dung kien thu'c hda hoc v^o ddi song va san xua't, giiip hpc sinh phat hi?n vk giai quyet nhO'ng v§n de th\ic lien dat qua dd kich thich s\i hu'ng thu, tri td md ldng say me nghien cu'u khoa hpc cong ngh? BTTT diTdc xky di/ng chi3 yeu du'a tren nguyen t^c va difPc ip dung thich hdp vko c5c gid day nh^m nang cao chS't lUOng day va hoc Hda hoc nhif: xay dtJng tinh huo'ng vao bai; hlnh kie'n thu'c mdi; v3n dung kien thu'c, u'ng dung; cung co' kien thifc luyen tap, thiJc h^nh, hoat dpng ngoai gid len ldp va boi dUSng hpc sinh gioi "Trirdng THPT chuyen Le Quy Don Binh Dinh NgSy nhan bai- 07/01/2013 ; Ngay nhan dang: 18/7/2013 ... EFFICIENCY ^ XAY D U N G VA SLf DUNG BAI TAP T H U C TIEN NHAM NANG CAO HIEU QUA DAY HOC VA BOI D U G N G HOC SINH GIOI HOA HOC CJ TRUCJNG TRUNG HOC P H T H N G Ngo Thi Ngoc Mai Bai tap hda hpc c6 npi... reacts with CO^, in the ak, and releases HCIO, so it has similar applications to Javel water : 2CaOCl, + CO, + H^O -^ CaCO^ + CaCl, + 2HC10 Calcium oxychloride is also used for bleaching textiles,... tien (BTTT) \k nhO''ng bki tap van dung kien thu''c hda hoc v^o ddi song va san xua''t, giiip hpc sinh phat hi?n vk giai quyet nhO''ng v§n de th\ic lien dat qua dd kich thich s\i hu''ng thu, tri td