VAN DUNG QUAN DIEM HOAT DONG TROMG DAY HOC TOAM d VH6 THOMG O TS NGUYEN THANH HUNG" NGUYEN CHI TRUNG" Theo J Piaget (1), tri thuc khdng phdl di/qe truyen thy \u ngt/di blS''''t din ngi/dl khdng biet md d[.]
VAN DUNG QUAN DIEM HOAT DONG TROMG DAY HOC TOAM d VH6 THOMG O TS NGUYEN THANH HUNG" - NGUYEN CHI TRUNG" T heo J Piaget (1), tri thuc khdng phdl di/qe truyen thy \u ngt/di blS't din ngi/dl khdng biet md duqe chinh chu fhef nhqn thuc xdy di^ng thdng qua cdc hoqt dqng (HD) hqe t§p Trong qud trinh dqy hqe (DH), tijy vdo tung bdi hqe md GV It/a chqn phuong phdp d q y hqc (PPDH) phu hqp vd thiet ke cdc HD hoe Idp hjong ung cho HS Vlee phdn tich mdt HD thdnh ede HD thdnh phdn giup G V td* chuc cho HS h^n hdnh cdc HD hqc tdp d muc d d vua sue D^ ede HD nhdn thuc cOo HS dqt hieu qud cao, doi hdi ngudi hqe phdi thi/e hien mot edeh ti/ gidc, ehu dqng vd tich cue Trong cdc HD hqc tdp, kS't qud dqt duqe d muc d o ndy cd the Iqi Id tien di de dqt dugc ket qud cao hon Do d d , GV edn phdn bdc HD theo nhi/ng muc khde Idm eo so cho viee thiet ke ede HD nhdn thirc cho HS, su phdn bdc cdng cy the thi hieu qud cua cdc HD cdng coo Quon diem HD DH cd the duqe thye hien d mot so' tu ti/dng chu dqo sou: Tqp luyen cho HS tht/c hien ede HD hqc t d p tucmg thich v o i n q i dung vd mye tieu DH - HS edn thuc hien dugc cdc HD hqc tap tuong thich vdi ndi dung DH: Mdt HD hqc tdp euo ngi/dl hqe dt/qc gqi Id tt/ong thieh voi ndf dung DH neu nd ed tde ddng gdp phdn kien tqo, cung co, hodn thien tri thi/c hoqe ren luyen cdc kt ndng, kT xdo cho ngt/di hoe - Trong DH, edn phdn tich mdt HD hqe tdp cdc HD thdnh phdn GV cd the r6n luySn cho HS edeh boo qudt vd'n de, cdch tdch rieng cdc HD hqc tdp can thiet Trong qua trinh glai quyet van d l , mot HD hqc tqp cd the dt/qc xud't hien nhu mdt thdnh phan cua mdt HD khde, - Lya chgn ede HD hgc tap dya vdo mye tieu DH: M o i nqi dung DH thi/dng hem tdng nhieu HO; nhl§n, de trdnh hien tirong ddn trdi c^n chqn Iqc cdc HD de tdp trung cho mot so' muc tieu nhd't dinh Vi dy: Sou HS hqe vi cdch dt/ng dudng vudng gdc ehung eua hai dudng thtSng cheo o vd b khdng gian, G V duo ro hai finh hudng sou nhfim giup HS tht/c hi§n cdc HD hqc tdp ttrong thich vdl nql dung: Tinh hud'ng 1: Dung mdt phdng (P) chua dudng thdng b va (P) vudng gdc vol dt/dng Hidng a, gqi A = af-.(P) Dt/ng AB b, B e b, to cd AB Id doqn vudng gdc ehung cua a vd b (hinh la) Tinh hud'ng 2: Dung mdt phdng (P) vudng gdc vol dudng thdng a , di/dng thdng b' Id hinh chllu cua dudng thdng b len (P) C5oi M = a n (P), M N b', NB / / a , BA / / N M Ta ed AB Id doqn vudng gdc chung euo a vd b (hinh lb) Hinh la & /^gy Hinh lb GV ygu edu HS trinh bdy Iqi edeh dung, de khde sdu kien thuc, GV cho HS gidi bdi todn: Cho hinh chop S.ABCD ed ddy ABCD la hinh vudng, SA J (ABCD) Dung dogn vudng gdc chung eua cdc dudng thSng: a) SC vd BD; b) SB vd AC; c) SB vd AD; d) SC vd AD Vdl edeh tqo tinh huong nhu vqy, HS duqe thuc hien nhieu HD thdnh phan nham chiim linh vd cting cd k i l n Hiuc G o i d q n g c o v d ht/dng d a n HS thi/c hl&n cdc HD hqc t d p GV can si/ dyng cdc PPDH phdt buy dt/qc Knh tich cue, tt; gidc, chii dqng, sdng tqo eua HS theo hudng g g i dqng eo thiie dd'y HS hgc tqp nhom dqt dugc cdc mye tieu d d Viee ggi ddng coeOo G V DH nhdm tqo hi/ng thij, su td md mud'n khdm phd tri thuc mdi * Tnrong fi;i hqc Tay Nguyen " 1^0 h ^ Uioa 19, TnrongfiaiIIQC stf ph^n Ha Noi Tap chi Giao due so (ic* a • ia/aon) cho HS qud trinh phdt hi$n vd gidi quyet tri thuc DH todn, d d Id: Tri thuc su vdt; tri vd'n d l , Neu G V cd PP su phqm td't, biet edeh ggi thuc PP; tri Hide chudn; tri thuc gl6 tn; d d , dgng co se khich le tinh than hgc tdp, phdt trien ndng luc khdm phd tri thuc cua HS GV edn hudng cho HS tdp trung khal thdc trgng tdm eua vd'n de nham dqt dugc yeu cau dqt Tuy nhi&n, viec tri thuc PP Id tri thuc cd y nghTa cdng cu, phuong tien de tien hdnh ede HD nhu phdt hlSn, Hm tdl, h'nh hql tri thuc, HD «quy /q ve quen" Id mdt HD b i l n gqi dgng co cua G V khong phdi chi dung Iqi d viee phdt b i l u , bien doi bdi todn md eon Id su khai thdc, tqo vd'n de mdi h> bdi toan ban ddu de ndng cao hiSu qud DH ehdng hqn, vdi bdi kran sou: Chodudng thdng d vd hai diim A, B ndm cung phia vdl d Tim diem M tren dsao cho MA + MB nhd nhdt Hudng dan (HD): Gqi A ' Id d i l m dd'i xung vdi todn hgc, giup HS d l ddng Hep cdn vd'n d l mdi qud trinh hqe tdp Thdng qua HD ndy, GV cd the dua n h l l u bdi todn mdi tu bdi todn ban d d u Vi dy: Sou hqe dinh nghTo vd cdc tinh chd't cua cd'p so nhdn, GV dan dcSt HS thuc hien ede HD hoc tdp phu h g p vdi tri thuc PP dd biet d l k i l n tqo tri thuc mdi thdng qua A qua d (hinh 2) Vdi mqi diem M thuqe d, to cd: M A + MB = M A ' + MB ^ A'B -> (MA + MB)^,^ = A'B * + y + x+2y+: x+y+2z bd't ddng thuc: — - ' " ' • ^ 72\ ^ •*•—*—^-\ Ix-i-y + z \6\x X y • » )• =) ' 7) Cho X, y, > v d x + y + z = xyz Chung I • XV V -X 'iJi (HD: ,{l+»v) x.i\^y.:) >'.(l+=jc) minh rdng: ^ _1_ I HS b i l n dd'i cdng thuc: z(\+xy) z z(l+.ry) - sou d d su dyng kef qud + >'+2z euo bdi tdp 6) Trong DH mdn Todn d phd thdng, GV edn thilt ke vd td' chuc cdc HD hgc tdp cd su phdn bdc cho HS mdt cdch hnh hoqt de phu hgp vdi tung ddi t u q n g , trinh d o euo HS, De tgo dugc mot khdng hgc tdp sol ndi, G V cdn khuyen khich HS thorn gio g i d l quyet v a n d e Do vdy, vdi cdc nhiem vy DH phuc tqp, G V nen chia vdn de thdnh cdc trudng hgp nhd, don gidn de HS ed the gidl quyet, sou d o ndng coo d d n muc Dual ddy Id mdt sd' bdi top minh hga dqy khd nhdm phdt huy tinh tich cue, khd ndng HS kl ndng d p dung bd't ddng thuc Cdsi vdo gidi khdm phd cua HS N h u vdy, neu GV vqn dyng cdc bdi todn thdng qua he thdng bdi tdp phdn cdc li thuyet ve quon diem HD mdt cdch thieh bdc tu dem gidn den phue tqp (thuc hien hgp vd sdng t q o thi chd't lugng DH se dugc mdt h i t dqy) ndng coo Q 1) Chirng minh rdng: f ' ' * " ] ! ' ' * ^ ] ^ ^ ! vol mgl a, b duong (HD: van dyng true tiip bdt ddng {1) J Piaget TSm l i hpc vd Gi^o due hpc NXB Gido (/((c, H.1999 2) Chung minh r&ig: a^ +1>^ + c^ ^ ajj-¥ b.c + ca, (2) Nguy£n Ba Kim Phinmg phdp d^y hpc mOn T o ^ vdi mqi o , b, e duemg (HD: ghep ddi) NXB Cidorf(Jc.H 2004 3) Chimg minh rdng: a^ + b ' + e^ + d ' + e ' £ Tdi li£u tham khap a(b + e + d + e), vol mgl a, b , e, d , e duemg (HD: Nguy£n B& Kim Hpc t$p hoat d^ng vd bing , , I , a' a' a' a' , hoatdOng NXB Gidodifc H.1999 tach a' = — + — + — + — ) A N, Leonchiep Hoat d