TIM HIEU KIEN THl̂ /C SUT DUNG KY THUAT TAG LAP TINH HUONG GO VAN DE TRONG DAY HOG TOAN a TIEU HOG TRAN NGOC LAN Trucrng DHSP Ha Noi 1 Dat van de Trong mpt sd nam gan day viec nghien edu sd dung phi/d[.]
TIM HIEU KIEN THl^/C SUT DUNG KY THUAT TAG LAP TINH HUONG GO VAN DE TRONG DAY HOG TOAN a TIEU HOG TRAN NGOC LAN Trucrng DHSP Ha Noi Dat van de Trong mpt sd nam gan day viec nghien edu sd dung phi/dng phap day hpc Phat hien va giai quyet van de (PH&GQVO) vao qua trinh day hpc eac mdn hpe d tieu hpe ndi chung va mdn Toan ndi rieng da dirpc nhieu ngufdi thifc hien Tuy nhien tren thirc te, viec trien khai cac ke't qua nghien cdu edn nhieu han che Mpt cac nguyen nhan ehu ye'u din de'n eac han che dd la Phat hien va giai quyet van de Nhieu nha nghien edu da khang djnh: Khdng cd Tinh huong cd van de (THCVD) thi khdng cd day hpc PH&GQVO Vay tao lap THCVO can ehu y gi de dat ddpc cap dp ky thuat va sd dung ky thuat dd nhif the nao day hpc toan d tieu hpc? Trong bai vie't chung tdi mudn trinh bay mpt sd nghien edu bifde dau gdp phan giai dap cau hdi neu tren Mot so ky thuat tao tinh hudng co van de day hoc phat hien va giai quye't van de Trong cud'n Phwang phap day hgc mdn Toan (trang 195 - 200), tae gia Nguyen Ba Kim da trinh bay each thdng dung de tao tinh hudng gpi van de (ndi theo each eua cac tac gia khac cung ehfnh la ky thuat tao THCVO) dd la: Dd doan nhd trure quan va thure nghiem (nhan xet, tfnh toan, dac) Lat ngu'pc van de Xem xet tddng tif • - Khai quat hda Yeu cau giai bai tap ma ngifdi hpe chira biet thuat giai Tim sai lam Idi giai Phat hien nguyen nhan sai lam va sda chda sai lam Chung ta deu biet cd dieu kien de mdt tinh hudng trd tinh hudng gpi van de hay THCVO dd la: Tdn tai mpt van de tinh hudng da neu, van de gpi nhu cau nhan thdc ddi vdi ngirdi hpe, van de khdi day niem tin d kha" nang ban than ngifdi hpc Nhif vay phan tfch mpt THCVO ta thay nd difpc cau bdi cac ye'u td sau: Tri thdc khoa hpe ma chiJ the nhan thdc chira biet, tinh trang tam ly va nhu cau cua chu the dd'i vdi tri thdc, vdn tri thdc va kha nang thure te cua chu the nhan thdc Nhif vay ye'u td tao nen tfnh ky thuat sd dung cae each tao 29 TiiwmiFll KIEN THUC THCVO neu tren the hien d chd dam bao van de ddpc dat d thdi diem thich hap, vdi dd'i tddng thfeh hpp ve mat nhu cau va kha nang SiJf dung ky thuat tao tinh huong c6 van de day hoc toan d tieu hoc Trong phan ehung ta xem xet viec sd dung ky thuat tao tinh hudng cd van de d khau chu ye'u day hpc mdn Toan d tieu hpe dd la: - Thd nha't: Hinh kien thdc mdi - Thd hai: Cung cd khac sau kie'n thdc da cd - Thd ba: Van dung sang tao cac kie'n thdc de giai quye't cac nhiem VLJ hpc tap 3.1 De kich thich hgc sinh tim tdi kien thdc mdi chung ta cd the sd dung ky thuat tao tinh hudng cd van de dd la: Difdoan nhd trwc quan va tht/c nghiem (nhan xet, tinh toan, dac ) Lat ngwgc van de Xem xet twang tif Khai quat hda Sau day xin neu vf du tddng dng vdi ky thuat ndi tren: Vi du 1: Tao tinh huong co van de de hoc sinh dd doan nhd trde quan va thdc nghiem ldp 3, de giup hpc sinh thay du'pe y nghTa cua dau ngoac va qui tac tfnh gia trj cua bieu thdc cd dau ngoac, giao vien ed the lam nhd sau: Xuat phat ban dau la bai tap tfnh gia trj cua bieu thdc 30 + : 5, hpe sinh hoan toan thdng nhat each tfnh gia trj eija bieu thdc Day la bieu thdc cd ea phep cpng va phep chia, ta thure hien phep chia trifdc, chia cho bang Tie'p theo, ta thifc hien phep cpng: 30 cpng bang 31 Oen day, giao vien dat van de: Ne'u mudn thirc hien phep cpng 30 + trifdc sau dd mdi thdc hien phep ehia cho 5, cae em cd the them kf hieu vao bieu thdc nhd the nao? Khi eac em nhan thdc ddpc nhiem vu cac em da vao trang thai tinh hud'ng ed van de Trang thai se keo dai sud't qua trinh di/doan va thd nghiem phwang an giai quyet Vi du Tao tinh huong bing viec lat ngdOc van de Khi hpc sinh Idp hpc ve da'u hieu ehia het cho 3, cac em da biet: Cac sd cd tdng cac chd sd ehia he't cho thi sd dd ehia het cho Sau thdc hanh, giao vien cd the tao tinh hudng cd van de bang each lat ngdpc van de hpc sinh da biet nhd sau: Yeu cau cac em hay xet xem 30 TIM HIEU KIEN THLfC cac sd cd tong cac chd sd khdng chia het cho thi cd chia het cho hay khdng? Khi nhan nhiem vu hpe sinh d vao tinh hud'ng cd van de Vi du 3: Tao tinh huong cd van de bing viec xem xet tddng ti/ Idp 3, giao vien cd the dat van de de eac em tur lap bang nhan Khi nhan thdc nhiem vu d thdi diem hpc sinh chifa bie't gi ve bang nhan va da hpc xong cae bang nhan pham vi thi hoc sinh se vao tinh hudng cd van de Vi: - Tdn tai mpt van de chifa biet, chda cd cau tra Idi bang nhan la the nao? - Thay can thiet cd bang nhan vi tifdng tir bang nhan 5, bang nhan ed tac dung td't tfnh nham - Thay tin vao kha nang ed the lap durpc bang nhan theo phifdng phap tddng td lap bang nhan * Xae dinh dang eua bang nhan 6: Tifdng tif nhan dang bang nhan (gdm may cpt la nhdng cdt nao? Cac gia trj mdi cpt lien he sao?) * Cach lap bang nhan 6: Ti/dng tir each lap bang nhan la dira vao eac phirong tien va dd dimg trirc quan de xae djnh cac ket qua va di;a vao quan he gida cae gia trj cpt ke't qua ma dien tiep cho de'n hoan chi'nh bang Vi du 4: Tao tinh hudng c6 van de vdi yeu cau khai quat hoa Yeu cau hpc sinh tim each cpng hai phan sd sau rdi rut each cpng phan sd khac 1 , , mau sd: - + - = ? Khi cac em nhan thdc di/de nhiem vu cac em da vao tinh hudng cd van de Vi: - Chu'a biet lam the nao de cpng phan sd da cho, chifa cd cau tra Idi (tdn tai van de) - Nhan tha'y can biet each cpng phan sd vi thirc te ed nhieu phan sd khac miu sd - Cam thay cd nhieu hy vpng vao kha nang la cpng dirpc vi dau dd da cd nhdng kien thdc lien quan Trang thai se keo dai sudt qua trinh lien he thd nghiem va dw doan khai quat hda each tinh 3.2 Degiup hpc sinh ciing cd, khac sau kien thdc da cd ta cd the sd dung ky thuat tao tinh hudng cd van de dd la: * Yeu cau tim sai lam Idi giai * Phat hien nguyen nhan sai lam va sda chwa sai lam Sau day la mpt sd vf du tirong dng vdi ky thuat neu tren: 31 TJM HIEU KIEN THL/C * Vl du ve sd dung ky thuat tao tinh hud'ng cd van de yeu cau hpc sinh tim Idi sai Idi giai eho trdde Vi du: Khi tfnh gia trj bieu thdc: (160 x - 25 + 275) x cd hpc sinh da dda each giai va ket qua nhif sau Hay xac dinh each giai diing va chi chd sai cae each giai edn lai Caeh1: (160 x 5-25 + 275)x2 Cach 2: (160x 5-25 + 275)x2 = (800 - 25 + 275) x = 800 - 25 + 275 X = (800 - 300) x = 800 - 25 + 550 = 500 x = 775 + 550 = 1000 = 1325 Cach 3: (160x 5-25 + 275) x2 Cach4: (160x 5-25 + 275)x2 = (800 - 25 +275) x = (800 - 25 + 275) x = (775 + 275)X = 775 + 275x2 = 1050x2 = 775 + 550 = 2100 = 1325 Vi du: Xac djnh sd dd dung vdi bai toan da cho va chi chd sai mdi sd dd cdn lai Bai toan: Tung cd 24 vien bi dirng d tui Neu chuyen vien bi td tui trai sang tui phai thi sd bi d tui bang Tim sd bi d mdi tui cua Tung, a Sd dd tdm tat ?bi Tui trai: Tui phai: 4bi 24 bi ?bi b Sd dd tdm tat ,?bi ^ Tui trai: ^ •24bi Tui phai: ?bi c Sd dd tdm tat Tiii trai: 24 bi Tui phai: d Sdddtdmtat4 Tui trai: 24 bi Tui phai: ? bi; Khi nhan nhiem vu hpc sinh da bu'de vao tinh hud'ng cd van de vi: - Chifa cd cau tra Idi, chifa cd thuat giai de chac chan tim chd sai 32 TIM HIEU KIENTHl/C - Hpe sinh tha'y cd nhu cau tim chd sai vi thupe pham vi kie'n thdc va vda hpc - Hpe sinh tin tirdng vao kha nang tim chd sai neu chju khd quan sat eac ket qua dang cd va vdi vdn tri thdc da hpc * Vf du ve sd dung ky thuat tao tinh hud'ng ed van de yeu cau hpe sinh phat hien nguyen nhan sai lam va sda chda sai lam Vi du: Xac djnh nguyen nhan sai lam cac bai giai cua bai toan sau va sda lai cho dung: Bai toan: Ldp 5A cd 50 hpe sinh, dd cd 27 ban nam Hdi sd hpc sinh nd cua Idp 5A chiem bao nhieu phan tram sd hpe sinh Idp? Bill giai Sd hpe sinh nd chiem sd phan tram cua hpc sinh Idp la: 27 : 50 = 0,54 0,54 = 54% Dap sd: 54% Bai giai Sd hoe sinh nd cd Idp dd la: 50 - 27 = 23 (hpc sinh) Sd hpe sinh nd ehie'm sd phan tram hpc sinh Idp la: 23:50x100 = 46% Oapsd:46% 3.3 Kich thich hgc sinh van dung sang tao kien thdc vao giai quyet nhiem VIJ hgc tap cd the sd dung mdt so ky thuat sau: 3.3.1 Yeu cau giai bai tap (bang mpt hoac nhieu each) ma ngifdi hpe chira bie't thuat giai Vl du: Trong dpt Tet trdng cay Idp 4A trdng difpc 21 cay, Idp 4B trdng di/pc 22 cay, Idp 4C trdng dddc 29 cay Tim sd cay cija Idp 40 biet sd cay trdng di/pc eua Idp 40 nhieu hdn trung binh cpng sd cay cija Idp la cay - Hpc sinh da bie't each tim sd trung binh cpng nhi/ng d dang chuan Cdn tinh hud'ng chda cd thuat giai - Hpe sinh thay cd nhu cau vi day la dang toan vda ddpc hpc - Hpc sinh tin tddng vao kha nang cd the giai quye't difpc bai toan ne'u suy nghT them ve cae dang da bie't de tim mdi lien he 33 TJM HIEU KIENTHL/C Rd rang, hoc sinh da d tinh hud'ng cd van de nhan nhiem vu tren 3.3.2 Yeu cau dat de toan theo so dd rdi giai: Vi dij: ? phut I ?phut 'v I ''''' ^ J ' ^phut I '^l I "^1 Bai toan 1: Hang ba ban An, Binh, Cifdng di td nha minh de'n trifdng Thdi gian di eua Binh gap lan thdi gian di cua An nhu'ng chi bang 3/4 thdi gian di cua Cddng Bie't rang 2/3 thdi gian di cua Binh la phut Tfnh thdi gian mdi ban phai di td nha de'n tru'dng Bai toan 2: Hang Hoa di hpc td nha den trifdng, ne'u Hoa di bp thi thdi gian di gap lan thdi gian ddpc me chd di bang xe may Neu Hoa td di bang xe dap thi thdi gian di gap lan thdi gian di bang xe may Tinh thdi gian di td nha Hoa den trddng bang mdi loai phddng tien, bie't rang 2/3 thdi gian Hoa di bang xe dap la phut Bai toan 3: Trong gid luyen tap mdn Toan, ban An da giai dirpc bai tap Thdi gian ban An giai bai tap gap lan thdi gian An giai bai 1, va bang 4/3 thdi gian An giai bai tap Tfnh thdi gian ban An da dung de giai mdi bai biet rang 2/3 thdi gian giai bai bang phut Khi hoc sinh thirc hien cac yeu cau tren, hpe sinh da vao tinh hud'ng cd van de, da thd nghiem quan sat thi/c te de sang tao van canh, sang tao eac ddi tu'png bai toan phu hpp vdi sdddda eho Tdm lai: Cac ky thuat tao lap tinh hudng cd van de khdng phai chi sd dung tdt d cae cap hpc tren ma hoan toan cd the sd dung cac khau eua qua trinh day hpe mdn Toan d cap tieu hpc Van de la giao vien can tim tdi de van dung dung npi dung, dung luc, dung chd va dung ddi tu'png TAI LIEU THAM KHAO Nguyen Ba Kim (2002), Phwang phap day hgc mdn Toan 1, NXB Oai hpe Sd pham Ha Npi Vu Qudc Chung (chu bien), Oao Thai Lai, Od Tien Dat, Tran Ngpc Lan, Nguydn Hung Quang, Le Ngpc Sdn (2007), Phwang phap day hgc toan a tieu hgc, NXB Oai hpc Sd pham Ha Npi Tran Ngpc Lan (2009), Thwc hanh phwang phap day hgc toan, NXB Oai hpc Su' pham Ha Npi 34 ... ve mat nhu cau va kha nang SiJf dung ky thuat tao tinh huong c6 van de day hoc toan d tieu hoc Trong phan ehung ta xem xet viec sd dung ky thuat tao tinh hudng cd van de d khau chu ye''u day hpc... 3.3.1 Yeu cau giai bai tap (bang mpt hoac nhieu each) ma ngifdi hpe chira bie''t thuat giai Vl du: Trong dpt Tet trdng cay Idp 4A trdng difpc 21 cay, Idp 4B trdng di/pc 22 cay, Idp 4C trdng dddc... trddng bang mdi loai phddng tien, bie''t rang 2/3 thdi gian Hoa di bang xe dap la phut Bai toan 3: Trong gid luyen tap mdn Toan, ban An da giai dirpc bai tap Thdi gian ban An giai bai tap gap lan