NGHIEN CU\J&Ul^G DUNG SU DUNG PHAN M E M CABRI HO TRO DAY HOC GlAl TOAN CUC TRI HINH HOC PHANG THEO PHUONG PHAP KHAM PHA Day hpc kham phi li phuong phap day hpc phat huy tinh tich cue ciia HS Viec ngh[.]
NGHIEN CU\J&Ul^G DUNG SU DUNG P H A N M E M CABRI HO TRO DAY HOC GlAl T O A N CUC TRI HINH HOC P H A N G THEO PHUONG PHAP K H A M P H A D ay hpc kham phi li phuong phap day hpc phat huy tinh tich cue ciia HS Viec nghien ciiu quy trinh day hpc khatn pha c6 ling dung phin mem Cabri day hpc giii toan cue tri hinh hpc phang se gop phin hinh va phat trien tu thuat toan, tu sang tao cho HS Day hoc kham pha Khim pha eo the hieu la qui trinh hoat dpng va tu bao gom quan sit, phin tich, nhin dinh, danh gii, neu gia thiet, suy luin, nham dua nhiing khai niem, phat hien rihiing tinh chit, quy luit, cac su vit, hien tupng va cac moi lien he giiia ehiing Theo [1], Bruner cho ring viee hpc tip kham pha xay cie ea nhin phai sir dung qua trinh tu de phat hien y nghia ciia dilu gi cho ban thin hp De c6 dupe dieu niy, nguoi hpc phii kit hpp quan sat vi nit ket luin, thue,hien so sanh, lim ro y nghia s6_ lieu dl tao mot sir hilu biet moi mi hp chua tiing bilt_ truoc Giao vien cin c6 ging va khuyin khieh HS tu kham pha eac nguyen li, ci giao vien va HS can phii thuc sir hoa nhip qua trinh day hpc Nhiem vu ciia ngudri day la chuyen tai cac thong tin cin hpc theo mot phuong phap phu hop vdi kha nang hilu bilt hieii tai ciia HS Giao trinh ciing cin dupe xiy dung theo hinh xoay 6c de HS dirpc tilp tiic xiy dimg kien thiic moi tren co so cai da hpc Tuy nhien, khong phii la HS TS Tran Trung, Truong Du bi Dai hoc Ddn toe Sdm San Nguyln Ngoc Giang, Cao hoc K18 - Truong Dai hoc Vinh tu khim phi tit ca cac dii lieu cong viec eua bin thin hom la thong tin, ma hp kham pha cong viec cua cac chuyen gia su lien quan giiia cae y tudmg lam hp cac em Phuomg phip va cac khai niem bang each sir eho phep HS hpc ma vui, dung nhiing eai da hpc tu tim cau tri Idi cho minh Co hai each tiep can va mot dieu giy nhieu tranh day hpc kham pha la day luin la phuong phip niy phat hpc bang each giai thich va trien dupe dpng co (hpc tip) day hpc bang each dat cau ben ehii khong phai la hoi: Trong day hpc bang each dpng CO ben ngoai giai thich, HS dupe giio vien De sir dung each kham phi giang kien thirc mdi, HS phai day hpc, truoc het cin sii dung vi ghi nha nhung kien phai xiy dung dupe eac bai thirc moi Con voi day hpc toan e6 tinh kham pha: la bii bang cich dat eiu hoi, giao toan dupe eho gom co nhirng vien dat eiu hoi hoac giao bii ciu hoi, nhiing bai toan tip yeu cau HS phai tu tim phan de HS tra loi kien thiic mdi, rnac dii viy van hoac tim each giai cae bai toan CO sir hudmg din hoae ehuin phin dan the hien cich bi dac biet Kien thiic moi giii bai toan ban dau Cich dupe giio vien ehinh sua va giai thudmg li nhung quy khang dinh lai Khim phi e6 tac hoac khai niem moi hudmg din la mot vi du eiia _ Cach xiy dimg _ bai toan each tiep can Day hpc de HS kham pha: Cin viet lai kham pha chi co the dupe sir cie bai toan theo hudmg thiet dung neu ngudi hpc co kha ke cac bai toan phin, nang nit dupe bii hpc mdi hudmg din each ghi chep ket tu kien thiic va kinh nghiem qui, dua cae ciu hoi din san CO ciia minh dit nham _ sau thuc hien Nhiing uu diem eua phuong cac yeu eiu dupe dua cho phap day hpc kham phi la: phep tim toi, kham, pha npi Khuyin khich dupe HS tham dung mdi Thiet ke cae bai gia, CO tinh dpng vien cao va toin thinh phan phii xuit phat vui Phin dat cau hoi lam tir logic hinh khai niem tang tinh ham hieu biet vi de bien cac bii toan tinh hiing thu cua HS doi voi mon toin, HS CO the thuc hien dupe hpc HS phii tu tirri hieu, tiic hoae bien cae thao tie la phii tu riam bat vin de hoat dpng vdd vit, voi dang,hoc Ket qua la eac em dung true quan Cac ciu hoi se hieu vin de, moi lien quan din dit phii dam bao giiip HS ciia no tdi bai hoc truoc vi cae quan sat, tu de tim cau em nha bii liu hom Phuong tri loi Viec tim ciu tri Idri phip niy khien HS phai c6 di dan hi de den khp, tir_nhung tu tot: danh gia, tu dieu bpc 16, de thiy den viec CO suy xet, giii quyet vin de, phat hien nhiing quy luit, khai phan tieh, tong hop HS duoc niem kli6ng tudmg minh, phai khuyen khieh coi viec hpc la th6ng qua phin tieh, khai quit Ngm- nhgn bai 20/7/2012: Ngay duyfl dang 25/8/2012 TAP CHI THIET BI GIAO DUC - SO 85 - 9/2012 Ill NGHIEN CUtJ&UlMG DUNG hoa mdi phat hien dupe., Sv dung phan mem Cabri ho trgf day hoc giai toan cue tri hinh hoc phang theo phvtfng phap Idiam pha a Quy trinh sir dung phan mem Cabri day hoc giai toan hinh hoc theo phuong phap kham pha Phin mem Cabri la ket qua nghien cim eiia phong thi nghiem cau tnic rai rac vi phuomg phap day hpc - Trurig tim nghien eiiu khoa hpc quoc gia - Truomg Dai hpc t6ng hpp Joseph Fourier Grenoble (Phap) Phin mern Cabri co cae ehlic nang de ve, dung bit ki mot hinh nio mat phang Ngudri dung co the thuc Men cac thao tac nhu "keo,", "tha.", "in", "hien", de the hien hinh ve duoi ritrihieu goc dp khac Phin mem Cabri co eac cong eu de tinh toan, kiern tra cic thupc tinh ciia cic d6i tupng hirih hpc mot cich true quari Phin mem Cabri cho phep ket hop giiia hinh hpc tong hpp va hirih hpc giii,tich de giai toan Cic buoc tien hinh umg dimg Cabri troiig giai toin cue tri hinh hpc phang nhu sau: Buac Dtmg hinh: Dung hinh theo yeu ciu ciia bii toan Co the ket hop vai mit lenh Interrupteur cho hinh xuit hien theo trinh tu Buac Tao vet: Do dai lupng cin tim cue tii phu thupc vio yi tri eiia diem hay hinh chuyen dpng Tir ve d6 thi ciia dai lupng vira phu thupc vao vi tri cua diem hay hinh ehuyen dpng Sau du doan cue tri xiy nio - Buac Chimg minh: Di ehuyen diem hay hinh ehuyen dpng den vi tri cho dai luong cin tim cue tri dat gia tri ldm nhit hay nho nhit, tii d6 suy loi giai cua bai toan - Buac Kiem chung: So sanh loi giai toan hpc va ket qui eua viec tim cue tri tren phin mem Cabri Neu hai ket qua khac thi chiing ta phai xem lai, loi giii toan hpc eiing nhu ket qua tim cue tri tren phan mem b Vi du minh hoa Vl du 1: Cho tarn giac ABC CO goc Akh6ng doi, t6ng dp dii hai eanh ben AB + AC khong d6i Tim tam giac eo chu vi nho nhit Giao vien dat eiu hoi:, Em hdy dung hinh yd ve thi cda dai luang cdn tim cite tri tren phdn mem hinh hoc dong Cabri ? HS thue hien viec tim tam giic CO, chu vi nho nhit tren phan mem Cabri nhu sau : * Buac Dung hinh: Dung doan thing B'C co vdi Ox tai M va Oy tai N cat tai E , * Buac^ Tao vet: Tao vet cho diem E, ehuyen, dpng diem A', ta thu dupe vet eua diem E Di ehuyen diem B' cho chu vi tam giac ABC nho nhit, ta thiy tam giac ABC can * Buac Chimg minh: Giao vien dat ciu hoi: Em hdy chung minh bdi todn tit kit qud du dodn cda phdn mem Cabri Neu duac hdy chung minh hdi todn bdng nhieu cdch khac ? + Cach 1: Dung tam giac cin AMN thoa man AM = AN _a ~2- Ke BH vi CK cung vu6ng goc voi MN Ta eo : tan BMH = tan CNK, suy BH _ KC MH NC Do BH = KC, suy MH = Ơ ã A ' M V A' \ C- dp dai a cho truoc Dung tren B ' C m6t diem A N6i B'A, A C Dung goc A Dung tren mot eanh cua goc A doan AB bang A'B' va tren canh lai doan AC bing A C (hmh ve) Dung he true Oxy cho hai true Ox vi Oy vu6ng goc vdi Dimg tren Ox mot diem M eho ,0M bang AB, tren Oy mot diem N cho ON bang chu vi tam giic ABC Cac dudmg vuong g6e • TAP CHI THIET BI GIAO DUC-SO 85-9/2012 NK,suyraBC> BK>KHva KH = MN Viy tatn giac cin AMN la tam giac ein tim + Cach 2: Ke BB" // MN Ta thiy hai tam giac MB"N va tam giic CNB co B"N = NC, B"M = NB, MB"N < BNC => MN < BC Viy tam giac can AMN li tarri giic cin tim *Buac Kiem chimg: Giao vien dat eiu hoi: Em hdy so jdnh kit qud chimg minh bang phuang phdp todn hoc vd kit qua kiem chung tren phdn mem Cabri ? ,Ldi giii toan hpc va ket qui kilm chiing tren phin mem Cabri la gidng NGHIEN * Birae Tao vit\ Tao vet eho diem E', chuyen dpng diem F, ta thu duac vet cua E' , Di chuyen diem F cho s6 d,6 dii dpan thing AB nho nhit, ta thiy dudmg nhu vuong gdc vdi AB * Buac Chimg minh: Giao vien dit eiu hoi: Em hdy Vi du 2: Cho goc xOy v i chung mink bdi todn^ tit kit dudmg trdn tim I ban kinh r qud dtt dodn cua phdn mim tiep xuc voi hai canh ciia goc Cabri ?Niu dugc hay chung xOy lin lupt tai D, va E Mot minh bdi todn bdng nhieu dudmg thing d tilp xiic voi cdch khde ? dudmg tron ( I ; r) tai F cat cac Tir diy ta eo cich giii Toin tia Ox v i Oy or A va B (F a hpc cho nd tren cung be DE) Xie dinh , - Cich 1: Theo tinh chit hai vi tri dirdmg thing ,d de dp dai tiep tuyen ciia dudmg tron cat doan thing AB ngin nhit tai m6t diem, ta c6: Giao vien dat ciu hoi:, Em BIF = i F l b v a F I A = i F I E Do AIB = EID (kh6ng hay dung hinh yd ve thi cda dai luang cdn tim ctrc tri doi) Tam giac lAB c6 AIB tren phdn mem hinh hoc dpng khong doi, eac gdc lAB v i Cabri ? HS, thuc hien viec tim gia IBA la eac goc nhon (vi lAB = tri ngan nhit eua AB tren cung i E A F