最新化学问题意识外文文献翻译.pdf

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1、 化学问题意识外文文献翻译 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 原文 题目：Using“What if.”questions to teach science Abstract With the widening knowledge base students will need to be more flexible in their learning habits.Traditionally,teaching school science often involves teacher-centred methods like lectures,exper

2、imental demonstration or guided inquiry.Plain knowledge dissemination will not adequately prepare students to cope with the changing world.Hence,schools need to train students to be reflective in their learning habits that is,getting students to be observant,to generate relevant alternatives and to

3、make sense of these ideas.This article discusses a well-documented reflective learning strategy-the use of“what if”questions,to help students extend their learning beyond curricular requirements.Students are introduced to a distillation set up and then asked to pose“what if”questions about it.Their

4、questions and the corresponding peer responses are a wealth of information for teachers to explore how science may be taught differently and with a greater impact on their students learning experience.Introduction The present science curriculum includes a range of student learning outcomes covering

5、laboratory and experimental science(MOE,2007).Researchers and scholars had argued that the roles of experiments and practical work in schools should allow students to practice laboratory skills,learn the various investigative processes and acquire first hand experiences in dealing with materials and

6、 laboratory wares(Boud,Dunn and Hegarty-Hazel,1986;Doran et al,2002;Hegarty-Hazel,1986;Josephsen,2003;Woolnough,1990).Besides these cognitive and psychomotor objectives of school laboratory courses,there are also suggestions that lessons should be made more attractive through more intellectually dem

7、anding courses and new teaching techniques that can motivate students to learn(Schmidt,2000).This paper discusses a well-documented reflective learning strategy-the use of questions posed by students to help them extend their learning beyond curricular requirements(Chin and Chia,精品好资料-如有侵权请联系网站删除 精品

8、好资料-如有侵权请联系网站删除 2004;Walsh and Sattes,2005).Specifically,it discusses the use of what if questions posed by students(Fogarty,1994).Students are introduced to a distillation set up and then asked to pose what if questions about it.Their questions and the corresponding peer responses provide teachers

9、with a good insight on how students contribute to knowledge building through self-created learning opportunities.The entire experience may also help to create a classroom teaching-learning culture in which the teacher takes on the role of the advanced learner among novice learners.Conducting the les

10、son Traditionally a lesson on experimental science would commence with teacher talk,student evaluation and then possibly,a confirmatory experimental experience in the laboratory.Inquiry-based lessons may tweak the lesson structure a bit,with the teacher starting a learning task by asking a question.

11、For example,“If you are stranded in the open sea on a small boat,how wou ld you go about making some fresh water to drink from the sea water around you?(Assuming you have the essential laboratory wares with you.)”The teacher may then follow up by facilitating a class discussion and end with the teac

12、her summarizing and contextualizing the discussion to fit the curricular requirements.Mortimer and Scott(2003)in their book,Making Meaning in Secondary School Science,suggested that students should engage in some form of dialogic activity if they are to develop an understanding of a science topic.In

13、 this respect,classroom talk,learning and meaning making would not make strange bedfellows but are essential features in the science classroom that would ensure students gain some impactful learning experiences.The lesson,which the present discussion is based on,involved both the traditional classro

14、om lesson delivery and the engagement of student dialogic process.It was conducted for a group of ten secondary three express students(equivalent to 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 grade 8).The students,four girls and six boys,were selected by their Chemistry teacher to attend a remedial lesson

15、on the topic of“Separation Techniques”.They came from two different classes taught by the same teacher.The separation technique to be revised in the 40-minute lesson was on“Simple Distillation”.The author of this paper was requested by their teacher to teach this remedial lesson.The author(referred

16、to as the remedial teacher in this paper)is also a qualified and experienced school science teacher of over 16 years.The proceedings of the lesson are summarized in Table 1.Approximate Time frame Learning/teaching events Pedagogical approach 10 minutes-Introduction -Importance of separation techniqu

17、es in chemistry-Example of a technique:Simple Distillation Teacher talk 10 minutes-Activity:Students to pose questions-First attempt:Invitation to verbalise the questions(nostudents volunteered)-Second attempt:Invitation to write down the questions starting with the words“What if.”(Students were obs

18、erved to be actively on task.)Reflective learning strategy:Use of“what if”questions to get students to observe the learning task and generate responses(in this case posed questions)20 minutes-Activity:Teacher-facilitated the discussion on the what if questions posed and written by the students on sl

19、ips of paper.-The slips of paper were collected and each students written questions were projected on visualiser and openly discussed by the students with comments and evaluative remarks made by the teacher.Students were instructed not to write their names on the paper.Reflective learning strategy:s

20、tudents engaged in meaning making(that is,attempting to answer,critique and perhaps re-phrase the questions so that some relationships can be established among the ideas generated).5 minutes-Summary:teacher summarised students responses to the learning tasks-Conclusion:teacher concluded lesson with

21、a review of the distillation method Teacher talk Table 1:Lesson Proceedings After the formal greetings and a simple self-introduction,the remedial teacher proceeded to explain the importance of separation techniques in chemistry.He cited 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 simple distillation as an

22、important technique that allows us to obtain a pure solvent or liquid from a contaminated liquid sample(a solution or a suspension).A fully labelled diagram of the apparatus set up for simple distillation was projected on the screen with the help of a visualiser(Figure 1).Referring to the diagram on

23、 the screen,the remedial teacher then proceeded to explain how the simple distillation apparatus works.The students were attentive and some were busy taking notes.This segment of the lesson lasted about ten minutes and was totally delivered by teacher-talk.Figure 1.Diagram of a simple distillation s

24、et up for distilling seawater.At this juncture,students were invited to verbally ask any question about the apparatus set up.There was a short pause with no response from the students.The remedial teacher then requested that they pen their questions on blank pieces of paper.Again,there were some“tho

25、ughtful”actions(for examples,a boy had his chin propped by his hand on the table and a few girls showed contorted eyebrows,all presumably deep in their thoughts).Most of them stared blankly at the diagram projected on the screen.Again,no one wrote anything.The remedial teacher then wrote the followi

26、ng words on the whiteboard “What if”and inst ructed students to begin posing their questions with these two words.He also added that they could ask anything about the apparatus set up,including the 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 materials,products,reaction conditions or anything that interest t

27、hem,so long as it was something related to the simple distillation process or apparatus set up.They could ask questions that they know the answers,or questions that they do not know the answers.No examples were given to the students other than these instructions.It was observed that students began t

28、o pen their thoughts,writing down the questions and raising their heads periodically to refer to the diagram shown on the screen.It took about ten minutes before most of them became exhausted of ideas and a few started to curiously peek into their neighbours work.The remedial teacher then collected

29、the papers and began to flash them one by one on the visualiser.For each students questions presented,the remedial teacher facilitated an almost spontaneous response from the floor.Students were observed to be chatty while a few showed amusements at their peers questions.There was a lively contribut

30、ion to the possibilities raised by the questions,including difficult and unfamiliar situations arising from questions like“What if there is no condenser there?”and“What if the Bunsen burner was replaced by a candle?”(Figure 2)Figure 2.“What if.”questions can surface unfamiliar experimental situation

31、s The“what if”questions and peer responses 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 The activity generated a list of 26 questions from the ten students(Table 2).These questions can be broadly classified into 11 different types of“What if”questions pertaining to the topic on simple distillation of seawate

32、r.Conditions Broad Questions Asked Frequency A Missing materials 1.“What if there was no boiling stones in the flask?”6 B Change in set up of apparatus(including missing pieces)2.“What if the positions of the water inlet and outlet of the condenser were switched?2 3“What if there were no thermometer

33、 in the set up?”1 4.“What if there were no condenser?”5 C Change in choice of apparatus or materials 5.“What if candle(s)was/were used in place of the Bunsen burner?2 6.“What if hot water was used in the condenser instead of cold water?”1 7.“What if the flask is made up of a different material(other

34、 than pyrex glass)?”1 8.“What if there are other particles in the seawater?”1 D Change in physical or environmental conditions 9.“What if the room conditions were changed(higher or lower than standard)?”4 10.“What if a smaller(Bunsen)flame was used?”2 E Unexpected experimental results 11.“What if th

35、e water distillate was tested to be impure?”1 Total number of“What if”questions generated=26 Table 2:Breakdown and frequency of the types of“What if”questions posed by students.(For the actual questions posed by students,please see Annex A)Unfortunately,the lively discussion during the presentation

36、of the students“What if.”question s was not documented on paper on the spot or recorded in any 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 media form.However,some typical examples of peer responses to the posed questions are summarized in Table 3.A few of the peer responses may not be technically sound and

37、some may be incorrect.It is important to have these misconceptions addressed immediately,and on the spot,by the teacher.This was done each time the teacher identified a misconception during the discussion.Table 3 also shows some examples of students misconceptions identified from their posed questio

38、ns and peer responses.“What if.”questions and typical peer responses 1.“What if there was no boiling stones in the flask?”Typical peer responses:a.“There will be no boiling in the water.”(Misconception)b.“Boiling will spill out of the flask.”(Possible,especially if“bumping”occurs and may cause the b

39、oiling liquid to spill out through the thermometer adaptor.)What could happen and why it happened:The boiling stones provide jagged surfaces for dissolved air to form small air Bubbles.This will prevent the formation of a big air bubble at the bottom of the flask which would attempt to“break free”,h

40、ence the“bumping”phenomenon.2.“What if the positions of the water inlet and outlet of the condenser were switched?Typical peer responses:a.“There will not be any liquid collected.”(Misconception)b.“There will be less liquid collected.”(Actual result)What could happen and why it happened:The directio

41、n of condensing medium(cold water)in the jacket of the condenser should be 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 opposing the direction of the hot vapour entering the condenser through the tube.This way,there will always be a maximal temperature gradient between the hot vapour and cold condensing medi

42、um,resulting in a large amount of vapour condensing into the distillate.By switching their positions,the temperature gradient will be greatly reduced and somewhere midway or so in the condenser,the temperature difference between the vapour and the medium may not be significant enough to continue a g

43、ood condensation process,hence the amount of distillate obtained will be reduced.3“What if there were no thermometer in the set up?”Typical peer responses:a.“I cannot do the experiment,because I cannot read the temperature.”(Fair enough,but distillation can still continue without the thermometer in

44、place.)b.“The distillation will be slower.”(Misconception)What could happen and why it happened:The thermometer serves only as a monitoring instrument in this apparatus set up.It does not contribute to the distillation process.The distillation will still continue as usual,at the same rate,with or wi

45、thout the thermometer.Table 3:Typical peer responses(verbal)to“What if”questions posed by students Discussion The teacher-talk section lasted about ten minutes.Students took about another ten minutes to think about how to pose and write down the questions.This involved closely studying the diagram o

46、n the projector screen,generating possibilities on how the questions may be written,and making sense of the questions and possible responses if they know the answers.This was what one student did she provided answers to her own questions.(See Annex A,last example)The next twenty minutes were spent o

47、n facilitating peer responses to the questions.It is interesting to note that the students came from two classes and may not 精品好资料-如有侵权请联系网站删除 精品好资料-如有侵权请联系网站删除 have known each other well.Although this is may be an assumption,what is amazing was that they were able to warm up to a total stranger,the

48、 remedial teacher,in just a couple of minutes.They were chatty and fully engrossed in contributing to possible answers to their peers questions.There was laughter,an occasional argument and of course,delightful comments like“Ah,we didnt know that!”or“Oh,now I see!”(for example,when the teacher comme

49、nted that theoretically,replacing the Bunsen burner with a candle would still lead to pure water being collected as the distillate,but in practice,this would be a slower and a less efficient process).They also expressed surprise that the thermometer is not an essential piece of apparatus in the set

50、up.The entire classroom learning experience threw up several interesting and noteworthy teaching-learning issues for science teachers.(1)Modeling real life learning experiences.Reflective learning strategies,like the use of“what if”questions,can be effectively applied to classroom situations.These l