以生活素材引入,在物理課教學(xué)中進(jìn)行發(fā)現(xiàn)學(xué)習(xí)

1、發(fā)現(xiàn)學(xué)習(xí)，是由美國(guó)心理學(xué)家布魯納提出的。其內(nèi)容是教師通過(guò)引導(dǎo)讓學(xué)生自己主動(dòng)學(xué) 習(xí)，概括出原理或法則，學(xué)生就會(huì)因?yàn)榘准旱陌l(fā)現(xiàn)去學(xué)習(xí)，去概括出原理或法則，效果上, 因自己發(fā)現(xiàn)而感到愉快和成就感的滿足而使學(xué)習(xí)貝有強(qiáng)大的動(dòng)力，另外，所得知識(shí)也會(huì)因此 深刻而不易遺忘，并能廣泛應(yīng)用于實(shí)際，還有助于智力的發(fā)展。呈現(xiàn)出的主要特征是強(qiáng)調(diào)學(xué) 習(xí)過(guò)程，強(qiáng)調(diào)宜覺(jué)思維，強(qiáng)調(diào)內(nèi)在動(dòng)機(jī)。以“電動(dòng)勢(shì)和閉合電路歐姆定律”課題為例。利用日常生活中的常識(shí)，在物理課組織學(xué) 生發(fā)現(xiàn)學(xué)習(xí)。山于引導(dǎo)的知識(shí)是h常?；钪袠O為熟悉的，學(xué)生會(huì)更有興趣和熱情參與到主動(dòng) 發(fā)現(xiàn)學(xué)習(xí)中。在課堂開始，提出以下問(wèn)題： 一節(jié)干電池1.5v, 1號(hào)電池到9號(hào)電池

2、都是1.5v, 1.5v指什么? 干電池“舊” 了后，還可以在電子鐘內(nèi)繼續(xù)使用，但電子鐘后而也寫明1.5v,為什 么？在這里，我們先組織學(xué)牛討論猜想1.5v的意義。最后，學(xué)牛大致有兩個(gè)猜想：猜想a： 1.5v是電池兩端電壓。猜想b： 1.5v是干電池中一個(gè)不變屋，反映干電池的屬性z。接下來(lái)，組織學(xué)生實(shí)驗(yàn)。實(shí)驗(yàn)現(xiàn)彖：干電池兩端電壓（稱路端電壓）是會(huì)變化的，電源 外電路電阻人時(shí)，接近1.5v；外電阻小時(shí)，比1.5v少很多。結(jié)果是猜想a錯(cuò)，1.5v不是指 電池的兩端電壓。垂新組織學(xué)生在實(shí)驗(yàn)結(jié)論棊礎(chǔ)上，再次去猜想假設(shè)。這時(shí)，學(xué)生思維比z前更加活躍。有一部分學(xué)生提出想法a：電了鐘的電阻比較人，因此，“舊

3、”電池用于電了鐘時(shí)，干 電池的兩端電壓還是較大，所以能給電子鐘供電。有一部分學(xué)生提出想法b：用新電池可以造一個(gè)舊電池。找一個(gè)黑箱，黑箱內(nèi)接一個(gè)舊 電池和一個(gè)大電阻串聯(lián)，對(duì)外供電。冇一部分學(xué)生提出想法c： 1.5v是一個(gè)不變量，干電池路端電壓變化，增加部分或減少 部分，是被干電池內(nèi)部分擔(dān)了。在相互討論過(guò)程屮，最后剩卜三種想法。對(duì)三部分不同想法的學(xué)牛分開處理。想法a的學(xué)生:先用多用電表測(cè)雖電子鐘的電阻r1和小燈泡的電阻r2,得出結(jié)論rl>r2o 引導(dǎo)學(xué)生用一個(gè)“舊”干電池和滑動(dòng)變阻器串聯(lián)簡(jiǎn)化等效?；瑒?dòng)變阻器較大吋，代表電子鐘； 滑動(dòng)變阻器較小時(shí)，代表小燈泡。用電壓表和電流表測(cè)滑動(dòng)變阻器兩端電

4、壓和流過(guò)電流。最 后，學(xué)牛觀察到實(shí)驗(yàn)現(xiàn)象：滑動(dòng)變阻器值很大時(shí)，兩端電壓接近于1.4 v,電流??；滑動(dòng)變 阻器值很小時(shí)，兩端電壓非常小。結(jié)論是：iu電池能在電了鐘里繼續(xù)使用，因?yàn)殡娏绥姷碾?阻人，路端電壓與1.5 v比較接近。另外，可以跟學(xué)生講明，用這樣簡(jiǎn)單的電路來(lái)代替較復(fù) 雜的電路，這是物理建模過(guò)程。想法b的學(xué)生：提供所需器材和材料。學(xué)生做了一個(gè)這樣的黑箱，在內(nèi)部，用滑動(dòng)變阻 器代替電阻r3與新電池串聯(lián)，對(duì)外供電。實(shí)驗(yàn)發(fā)現(xiàn)：r3很小，黑箱衣現(xiàn)為一個(gè)新電池；r3 為幾歐吋，mih電池一模一樣。結(jié)論是：新電池和舊電$也的“1.5v”是一樣的，是不變的。 不過(guò)，舊電池的電卩fl大于新電池的電卩fl想

5、法c的學(xué)生：首先跟學(xué)生探討測(cè)量干電池內(nèi)的電壓是非常困難的。為了實(shí)驗(yàn)方便，用 鉛蓄電池代替干電池，用兩個(gè)電壓表分別測(cè)蓄電池內(nèi)電壓和路端電壓。用一個(gè)滑動(dòng)變阻器作 為外電路，可以改變外電阻大小。最后實(shí)驗(yàn)現(xiàn)彖：外電壓減少，內(nèi)電壓就增加；外電壓增加， 內(nèi)電壓就減少；并且外電壓和內(nèi)電壓z和是不變的等于2v （類似于干電池1.5vo）實(shí)驗(yàn)結(jié)論 是：蓄電池2v是不變。通過(guò)分析，最后結(jié)論是：干電池的1.5v是不變的，1.5v反映了干電 池的一個(gè)特性。布置學(xué)生課外閱讀課木電動(dòng)勢(shì)和閉合電路歐姆定律兩節(jié)。分成8個(gè)學(xué)習(xí)小組解 決兒個(gè)問(wèn)題：t電池1.5v反映了干電池的什么特性。用閉合電路歐姆定律解決為什么 舊電池能在電子

6、鐘上繼續(xù)使用。到第二節(jié)，抽一個(gè)學(xué)習(xí)小組到講臺(tái)上講解。第二節(jié)課上，抽到一個(gè)學(xué)習(xí)小組。這個(gè)學(xué)習(xí)小組，通過(guò)板廿講解內(nèi)容大致如下：在干電池中1.5v是通過(guò)化學(xué)反應(yīng)（非靜電力）把1c正電荷從負(fù)極搬至正極做功1.5 j 使其電勢(shì)能增加1.5 j, 1.5 v=1.5 j/c,這個(gè)數(shù)值由電源本身非靜電力性質(zhì)決定，命名電動(dòng)勢(shì) e=1.5vo并且指岀了不同型號(hào)干電池雖然人小不同，但是化學(xué)反應(yīng)（非靜電力）是一樣的, 因此它們電動(dòng)勢(shì)都是1.5 v；另外，鉛蓄電池非靜電力不同，所以電動(dòng)勢(shì)e不同。這個(gè)學(xué)習(xí)小組準(zhǔn)備比較充分，講授效果非常好。并h.他們提出想請(qǐng)教化學(xué)老師能否將iii 電池增加溶液濃度來(lái)減少電阻，讓它變成“新

7、”電池，還有學(xué)牛準(zhǔn)備解剖電池等許多新想法。教師組織學(xué)生學(xué)習(xí)時(shí)，從生活經(jīng)驗(yàn)導(dǎo)入更帶冇親和力，讓學(xué)生無(wú)障礙地投入到發(fā)現(xiàn)學(xué)習(xí) 中。組織學(xué)生發(fā)現(xiàn)學(xué)習(xí)，止學(xué)生認(rèn)識(shí)從表彖到本質(zhì)，從生活常識(shí)上升到理論，從特殊現(xiàn)象到 解決一般問(wèn)題。學(xué)生在發(fā)現(xiàn)錯(cuò)誤后自行改正，在討論后猜想通過(guò)實(shí)驗(yàn)驗(yàn)證，在強(qiáng)烈的好奇心 張使卜通過(guò)閱讀有關(guān)資料滿足欲望，在討論思考后向外拓展自己的眼界，其所產(chǎn)牛的正反饋 作用，遠(yuǎn)比外在獎(jiǎng)勵(lì)更加有價(jià)值。discovery learning, is put forward by american psychologist bruner. its content is a teacher by guidin

8、g let the student active learning, summarizes principle or rule, the student will because his findings to learn, to summarize the principle or rule, effect, for his discovery and feel happy and satisfied and make the learning with a strong power, in addition, the knowledge will be so deep and not ea

9、sy to forget, and can be widely used in practice, also conduce to the development of intelligence presents the main characteristics of the is to emphasize the learning process, emphasizes the intuitive thinking, emphasis on intrinsic motivation.with “electromotive force and closed circuit ohrrfs law

10、11 project as an example use common sense in daily life, students find learning in physics class organization. due to guide knowledge is very familiar in daily life, students are more involved in the active discovery learning interest and enthusiasm.at the beginning of the class, and put forward the

11、 following questions:(1) section 1.5 v dry cell, 1 to 9 battery is 1.5 v, 1.5 v?(2) dry cell after the ''old11, still can continue to use within the electronic clock, but the back of the electronic clock is 1.5 v, why?here, we organize students to discuss first guess the meaning of 1.5 v. fi

12、nally, the students have two guess roughly:suppose a: 1.5 v is on both ends of the battery voltage.suppose b: 1.5 v is not a variable in the dry cell, reflects one of the attributes of dry cellnext, organize students to experiment experimental phenomena: dry cell (called a terminal voltage) on both

13、ends of the voltage will be cha nge, power supply for large exter nal resista nee is close to 1.5 v; exter nal resista nee hours, a lot of less tha n 1.5 v. result is guess a fault, 1.5 v is not refers to the ends of the battery voltage.reorganize the students on the basis of the experimental conclu

14、sion, again to guess hypothesis at this time, the students' thinking more active than before.some students ideas a: the resista nee of the electronic clock is bigger, therefore, the "old” batteries used in the electronic clock, the ends of the dry cell voltage is larger, so can give power e

15、lectronic clock.some students proposed idea b: one of my old battery with new batteries can build looking for a black box, inside the black box after another old batteries and a large resistance in series, external power supply.some students ideas c: 1.5 v is an invariant, dry battery terminal volta

16、ge change, increase or decrease part, in ter nal shared is dry cell.in the process of mutual discussion, the last remaining three ideas handled separately to students of three different ideasthoughts of a student: use first multimeters measurement electronic clock resistor r1 and small bulb resista

17、nee r2# con elusion r1 > r2 guide the student to use a ,oldh series dry cells and slide rheostat simplified equivalent slide rheostat is larger, on behalf of the electronic clock; slide rheostat is small, on behalf of the small bulb. with voltmeter and ammeter cehua rheostat on both ends of the v

18、oltage and current flows through the fin ally, stude nts observed experime ntal phe no me na: slide rheostat value is large, both ends of the voltage close to 1.4 v, current is small; slide rheostat value is very small, very small voltage on both ends. conclusion: old batteries can continue to use i

19、n the electronic clock, because the resista nee of the electr onic clock, termi nal voltage close to 1.5 v. in additi on, you can talk with the students to say, i n this simple circuit in stead of the more complex circuit, this is physical modeling process.idea b students: provide the required equip

20、ment and materials. students made such a black box, i nside, use the slide rheostat in stead resistance r3 and new battery series, exter nal power supply. it was found that: r3 is very small, black box is a new battery; a few european for r3, and old batteries the conclusion is: the new and old batt

21、ery h1.5 vh is the same, is a constant. however; the resista nee of the old batteries is greater tha n the resista nee of new batteries.idea c student: first with the student to explore in the measurement of dry cell voltage is very difficult. for experime nt is convenient, use the lead in stead of

22、dry cell battery, with two voltmeter to measure battery voltage and the terminal voltage. as the external circuit, with a slide rheostat can cha nge the resistance size finally the experimental phe no me non: exter nal voltage decreases, the voltage in creases; outside voltage increases, the voltage

23、 is reduced; and outside is a constant equal to the sum of the voltage and the voltage within 2 v (similar to a 1.5 v dry cell. the experimental con elusion is that the 2 v battery is constant. through the an alysis, the final conclusion is that the battery 1.5 v is constant, 1.5 v reflects a charac

24、teristics of dry cell.decorate students extracurricular reading textbooks "electromotive force11 and ''closed circuit ohm's law" two. divided into eight study group to solve several problems: (1) dry cell 1.5 v reflects what properties of dry cell. (2) use closed circuit ohm

25、9;s law to solve why old batteries can continue to use on the electronic clock in the second section, a study group to the podium.the second class, to draw a study group this study group, through blackboard writing on content is roughly as follows:1.5 v in the dry cell by chemical reaction (non elec

26、trostatic force) move the 1 c positive charge from the cathode to the anode power 1.5 can in crease 1.5 j j make its pote ntial, 1.5 v = 1.5 j/c, this value is determined by the power supply itself nature of the electrostatic force, named electromotive force e = 1.5 v. and points out the different t

27、ypes of dry cell although the size is different, but the chemical reaction (non electrostatic force) is the same, so they all electromotive force is 1.5 v. in addition, lead battery of electrostatic force is different, so different electromotive force e.the study group to prepare more fully, teachi ng effect is very good. and they pu