GOV DONG c a NHOfTRirC QUAN TRONG DAY HOC KHAI NIEM HlNH HOG II TRlTllNG TRONG HOC GO SD ThS L U O N G V A N C A U " Hoat ddng hda ngudi hoc ddi hdi hpe sinh (HS) phaicdythiicvenhung myc tieu dat rava[.]
GOV DONG c a NHOfTRirC QUAN TRONG DAY HOC KHAI NIEM HlNH HOG II TRlTl NG TRONG HOC GO SD ThS L U O N G V A N C A U " H oat ddng hda ngudi hoc ddi hdi hpe sinh (HS) phaicdythiicvenhung myc tieu dat rava tao dU(?c ddng lue bentrong, thuc d^y hogt dpng dedatdupc mye tieu dd.Dilu duoc thd'hien dgiy hpc qua vide neu ro mye tieu va goi ddng eo (GDC)hpetapchoHS.Theo(1;tr.142):G0£:/a/am cho HS COy^dc vey nghia eua nhung hoat dgng va cua da U/gng hoat dgng GDC nhim lam cho nhdng myc tieu supham bien mue tieu cua ca nhan H$ chd khdng phai chl la su vao bai, dat van de mgt each hinh ^dc Phan ldn cac khai niem hinh hpe d trudng trung hpc ca sd (THCS) duoe hinh theo dudng quy nap ma theo do, tn/c quan ddng vai troratquan trpng.Tare quan lasuhdtrcf, giup HS tao bieu tucfng, phat trie'n tu ddn den hinh khai niem Vi vay, bai viet tap tmng vao viec GDC dgy hpc eae khai niem hinh hgc dtrudng THCS nhdtn/cquan, nd'i bat la mot so each thiic GDC duoc neu dudi day: GDC day hoc khai niem hinh hoc d THCS thong qua quan sat 1) GDC^ nhd quan sat str vat hoac tranh anh res(r i^lf.Oday/sy var cdthe bao gom ca vat that, sukipn, hi§n tupng; iranh anh ve s u v a f bao gom ca anh chyp va hinh ve ve vat that THCS, giao vien (GV) can su'dyng eae sy vat, tranh anh minh hpa cho HS, giup cac em khSc phue nhQng khd khan ban dau khillep can vdi khal niem mdi, hieu duoc toan hoc hk nguon tdddi song thuc te'nhu the nao, ,y Vidg /.-GDC hpe tap ve khai niem hinh chu' nhat d.:lop qua viee cho HS quan sat mat eua quyen saeh, mgtcaibang.matvien gach lat nen nha, Qua trinh tim hieu cac hinh nhu vay giup HS hieu rd hon ve eae vat d xung quanh DlGDChpetgpmdtsd'khainiemtnjTu tupng, GV cdthephwhopcachthLfcGDCnhdquan sat vat thgt vdi quan sat hinh ve, nhan xet tren hinh ve Vidu2:GBC hpc tgp khainiem dd'i xung toied Idp Hoatdgng /.'GV hudng dan HS quan sat mat dong ho treo tudng va nhgn xetve tung ddi vach vj tri (ki 2-.8/2013)- giOa cac cap s6(1 va 11), (2 va 10), (3 va 9), (4 va 8), (5 va 7) so vdi 'Injc" thing dung di qua vach gid va 12 gid Hoatdgng2:Qy dua hinh ve (dung bang phy hoge trinh ehieu) cho HS quan sat va nhat xet dae diem md'i quan he cua^cac cap diem (A, A'}, (B, B'), (C, C) so vdi dudng thing d {hinh 1) d Luu y: GDC day hpc khai niem nhd quan sat su vat hoac tranh anh ve suvat thudng dupe ap dyng day hgc cac khai niem de tim eude song Vugt khdi tae dyng GDC, cac vi dy neu tren cdn cd tac dung cho HS thay suton tai eua mdt logi dd'i tugng cua khainiem 2) GDC nham ggi iai hinh anh su vat da dugc quan sat qua khu Trong each GDC nay, de' nhan thu'c duge, HS ean sudung tri tudng tugng cua minh dmdt mde dp nhat dinh nao dd Qua trinh su dung nhung hinh anh nhuvaysegiup viee van dung phuang phap true quan vao day hpe duge thuan Igi bdi khdng phai luc nao eung cdthe tao dugc vat that dtren Idp Khi HS da eddu kien thuc vetunhien vaxa hpi thi vat that ddi trd nen khdng can thiet cae tiet hpe 1//rfi//.-GDC hpe khai niem hinh tnjo\dg GV hudng d i n HS hinh dung mdt hop sua, khoanh gieng khoi (phan ndl tren mat dat) cho ta hinh anh cua hinh gi? Cach tim hie'u hinh nhu vay se giiip HS hieu rd hon ve cac vat the gidi xung quanh * Sd Van hoa, The Hiao va Du Ijch Hai DUOng Tap chi Gido due so 316 47 Vidu2: DS'GOC hpc khai ni?m tiigiaci!\ilf 8, GV gdiycho HS (vOng nong thdn) hinh dung m^nh ru$ng cua gia dinh Tuong lu, cac khai niem: lam giac cdn didp 7; hinh thangd\dp 8; hinh ndn, hinh cau d Idp co the dupc GDC theo each tren i.i/uy.GOC nhdgpi lai hinh anh suvat da dupc HS quan sal tn^ng qua khdcd the dupe lien hanh day hpc cac khai niem ma HS da dupe lam quen didp dudi, cd nguon goc Id thuc tiln nhung da dupc cai bi§'n dua vao idp hpc Khi chpn hinh anh tn/c quan, uu lien chpn cac hinh anh gan gui vdi thuc te cupc sdng 3} GOC nh&quan sat mo hinh hinh hoc khdng gian, bieu ddva kihieu tuang trung cho vat that HS CO the nhan thdc su vat, hien tupng xung quanh nhdmd hinh hinh hpe khdng gian, bieu do, ki hieu Tnidng hpp thudng dien dcac Idp idn (Idp 8, idp 9), bdi nang luc luduy InJu tupng cua HS da phattrien dmdc dp cao hon GV eung ed the GDC eho HS td viec quan sat bieu Ven Khi GDC hpc lap cac khai niem vehinh hpc khdng gian (idp 8, idp 9), ngudi ta thudng phdi hpp giua cac hoat dpng tren vat that, tranh anh, hinh anh tri nhdve vat that, mo hinh hinh hpc khdrig gian, bieu va ki hieu tupng In/ng cho vat that Ch^ng han, GV cd the GDC cho HS qua cac hoat dpng sau: - Hudng d i n HS quan sat tren vat that, tranh anh ve vat that, hinh anh tri nhd, mo hinh d mpt vai dang khac nhau; -TnJu lupng hda bjng each sudung eae hinh ve, ki hieu loan hpc ViduQDC hpc khai niem dudng th§ng song song vdi mat phing didp Suot; (.'GV CO thechoHSthuc hien cac hoat dong nhu:-ChoHS xem mol que nhua vampi lam gd phang da dupc dat cho que song song vdi tam g6{nhung GV ehua dua td"song song"); - GV yeu cau HS neu them mpt vai hinh anh thuc te ve vj tri cua dudng thang va mat phang tuong lu nhu que nhua va lam gd ndi Iren; - Cho HS dua vao hinh 771am viee Iheo hoat dpng [ ? i d S G K (Toan 8, tap 2, In 99) Budc 2: Can eu vao kel q u a d hoal dpng @ ndi tren, HScd the ghi tdm tat: feB cz mp(A'B'CD') AB // mp(AB'C'D') o -IA'B'C mp(AB'C'D') l^B // AB' Khdng ehi cd tac dung GDC, each lam Iren cdn giup HS nhanh chdng khae sau kien thdc dudi dang cac ki hieu loan hpe GSC hoc t^p khal niem thong qua lamtKw chi din ho|c lam theo miu - U Cac hoatdpng iam Iheo cft/rf/ndsaohgiao khoa (SGK) hoac phieu hpc tap va ldm Iheo m / u ( G V lanj mSu va hudng dan, HS quan sal va lam theo) cd the hd Irp day hpc khai niem ndi chung va GDC hpc t|p khai nipm ndi rieng Mpt sddang hoatdpng iam Iheo chi d i n va iam Iheo m i u thudng dupe siidung nhu: ve hinh, gap gia'y, dac r ; G O C ( u - i ' / & i ' e / i ; n / i Neu H S t n / c B ^ v e dupc mdt hinh dng vdi mdt khai niem hinh hpo se gdp phan GDC cho cac em hpc khai niem Khdng chieo tae dung GDC, hinh ve giup HS hinh dunjcac v|tthe lh§' gidi khach quan, phat trien nang luc quan sat, phSn tich, md ta, phat trien tri tudng IUdng khdng gian, la chd dua tn/c giac cho viee n i m virng kh^t niem B§n canh viec ren luy§n cho HS ki nang sil dung cac dung cu truyen thdng nhu: th ude thang.thudc cd chia khoang, compa, eke GV can hudng dan eho eae em lam quen vdi ve hinh tren may vitinh va eae phan m i m tin hpc I'/du; GDC hpc tap khai niem doan Ihang didp HS ve theo chidan hoac lam Iheo m i u : danh dau hai diem A, B tren trang giay, dat canh thudc thing di qua diem A, B rdi lay dau chi vach theo canh thudc td A den B Net chi tren trang giay ia hinh anh cua do?n thing Ap (Toan 6, lap 1, tr 114) Viec tao dupc doan thang gdp phan GOC hgc khai nipm Khi Sl) dung nhiing dung cu ve hinh nhu Ihudc thang, compa, Ihudc cd chia khoang cdn hd trp cho HS lam quen vdi nhiing ddi tupng cq ban cila hinh hpc nhu: diem, dudng thang, doan thing, 2) GDC tu viec gap hinh Gap hinh la mpt hoal ddng tmc quan hd Iro cho qua Irinh hpc tap cua HS them phong phu, da dang, giup cac em nhan biel mplsdkhai niem hinh hpe mdi Vi vay, GV nen hudng d i n HS gap hinh de'GBC hpctap khainiem mptcaeh tu nhien va cd y nghTa thiet thpc l//Vu.'DeGDC hpc tap khai niem hai dudng thing vuong gde, GV cdthe hudng d i n HS gap ddimpttd giay, sau gap ddi lln niia dehinh giiia n§'p gap Vila cd, trai phang td giay roi quan sat hai n ^ gap cddudo va cac gde 1^0 bdi hai nep gap dd Cdthetd j ^ hai nep gap b l n g but va thudc t h i n g Sau dd, GV cho HS lay mdl Id giay khao, gap hai lan theo nhu hinh d SGK, trai phang td giay rdi quan sat hai nep gap cd dude va cac gde tao bdi hai nep gap (Toan 7, tap 1, tr 83-84) Cd the td lai hai nep gap blng B l * va thudc thang Vupt khdi ticdung GDC,vidu edn cdtac dung t^o linh hudng vao bai, chi suton 48 Tap chi Gido due so 316 -(kl2-8/2013) tgi cua 001 iupng va tao Dieu tucfng eho hogt ddng tu sau Cach GOC thdng qua gap giay thudng duoe sd du^khj^day hpc ,cac khai niem Vd dudng trung true' ,cu9m|idogn thirrg, tia phan giac eua mpt gde Ngoai ra, hoat ddng gap hinh cdn dugc ket tipp vdi hogt j56ng,cat, ghep hinh de tgo nen nhiJng hinh hinh hpc rifiu: hinh vuong, hinh tam giac, hinh trdn f 3) GDC thong qua dac Hoat ddng dac khdng ehi cdtac dung GDC macdn gdp phan giup HS hpe kien thu'c mdi, dong thdi, ren luyen kTnang thao tae vdi cac dyng cy hinh hoc, tgo hyng thu hpe tap, ren luyen tinh can than, chinh xac cho cac em Vidu: GOC hpc tap khai niem dp dai dogn thing (loan 6, tap 1, tr 117) thdng qua hoat dpng dgc Oedo dp dai dogn thing AB, GV dung thude cd chia khoang mm (thudc do dai) va lam nhu sau: dat canh cua thudc di qua hai diem A va B cho diem A tnjng vdi vgeh so 0, gia sir diem B tmng vdi vach 17(mm), tacddpdaidoan thang ABb^ng 17mm tiilfl/y;Cac khai nigm hinh hgc d Idp 6, Idp dugc xay dyng tiieo kieu md ta, dua vao hinh ve roi nang dan miic khd, mde tmu tupng, khai quat, thich hgpvditrinhdptuduycua HS nen cae hoatdpng lam theo chi d i n va lam theo mliu (ve hinh, gap gia'y, dgc) thudng duoc si} dyng viec tiep can khai nigm, dac biet la GOC GDC day hpc khai niem thdng qua cac hoat dpng ling dung thuc tien l//du;GOC hpctap khai niem gde ndi tie'p didp GV yeu cau HS ve ngdi canh deu (ehua hudng din ve dudng trdn) nhSm giup cac em khdi dong suy nghlve nhiem vu dugc giao Hinh anh ngdi ratquen thude vdi HS vi eae em thudng tha'y tren la Quoc ki eua Viet Nam,tren mu anh bd dpi, den dng vac djp Tnjng thu Tuy nhien, de c5t dupc ngdi th^t deu dan, can dd'i la dieu khd khan De giup HS khac phye khd khan nay, GV gpi y: cdng viee cd thedl dang hdn neu ta xem cae eanh lanhu'ng goc cd dinh nam tren mpt dudng trdn va mdi canh cua goc chiia mdt day cung eua dudng trdn dd (lue nayOVseduara/i/nft^) Saudd,GVtleptycgdiychoHS dya vao hinh ve hi/cquan (khdng chung minh) de ve ngdi sao5 canh bang each ve mdt dudng trdn, dung thude gde chia dudng trdn dd eung trdn blng nhau, tiJ'ddxac (^nh dinh ngdi va ve dugc ngdi Tdiday,GV hoan tat khau (30Cm(?6arNhung gde cd dinh niim tren dudng trdn va hai eanhfChiJa (ki2-812013)- hai day eung cua dudng trdn ddnhudhinhve trdn dupc gpi la gde ngi tiep va chiing ta se 6uqc hge bai nay" Trong bai: Vudng tron ngoai tiep Dudng tron ngi tiep" (Toan 9, tap 2, tr 90-91), GV nen quay Igi vidu d Hinh tren vayeu eau HS (cd thechi dd'i vdi HS kha gioi) giai thich cd chdng minh chat che each ve ngdi canh, bdi dd, HS da eddu kien thde toan hpcde khing dinh ranged mdt dudng trdn di qua ca dinh cua mgt ngu giac deu batki Nhuvay, GV da G0C/feh/iuccho baihge gde ndi tiep GDC day hpc khai niem xuat phattu npi bp toan hoc 1}GDCnhdtuangtt/hoa Vidu:QeGBChgc tap vetd giac, SGK da neu cau hdi: mdi tam giaced tong eae goc bSng 180°, cdn tugiac thi sao? (Toan 8, tap1,tr.64) 2} GDC nhd khai quat hoa Khat quat hda la thao tae tu di td mdt nhdm dd'i tuang sang mdt nhdm ddi tugng Idn hon ehua nhdm ban dau K/da'OeGDCkhidgyhgevedagiae,SGKdaneu cau hdi (dugc ddng khung): tam giae, tugiac dupc gpi chung la gi? (Toan 8, tap 1, tr 113) 3) GBC bing each lam xua't hien do'i tugng can nghien cuu Wrfu.GDC day hpe khai niem ti sd lucmg giac cua goc nhgn d Idp thdng qua hoatdgng ve hai tam giac vudng dong dang {hinh 3): Hoatdong 1:HS lam bai tap sau: Cho fes^BC va fev^'B'C, cdS = S' = 90° Chung minh rang: B= i ~ A'B' ' B' Hinh Hoat dgng 2: Gol AB laegnhkeeuagdcB, ACIa eanh dd'i eua goc B (tuong tyA'B'la eanh ke eua gde B', A'C' la canh ddi cua gde B') Td ket qua bai t o ^ tren hay cho biet, hai gde S" va T bang nao? G V dua ke't luan: ti so giiia cgnh dd'i va eanh ke cua mdt gde nhpn tam giae vudng dac trung (Xem liep trang 57} Tap chi Qiao due so 316 | 49 ... gui vdi thuc te cupc sdng 3} GOC nh &quan sat mo hinh hinh hoc khdng gian, bieu ddva kihieu tuang trung cho vat that HS CO the nhan thdc su vat, hien tupng xung quanh nhdmd hinh hinh hpe khdng gian,... HS quan sal tn^ng qua khdcd the dupe lien hanh day hpc cac khai niem ma HS da dupe lam quen didp dudi, cd nguon goc Id thuc tiln nhung da dupc cai bi§''n dua vao idp hpc Khi chpn hinh anh tn/c quan, ... niem Khdng chieo tae dung GDC, hinh ve giup HS hinh dunjcac v|tthe lh§'' gidi khach quan, phat trien nang luc quan sat, phSn tich, md ta, phat trien tri tudng IUdng khdng gian, la chd dua tn/c