VE HE THONG NANG LUG DAY HOC CUA NHA GIAO TRONG CAC CO S d GIAO DUG NGHE NGHIEP theo tiep can ndng tuc thuc hien TS VuXuanHCing Vien trudng Vien Nghien cdu Khoa hoc day nghe r Tom t5t Bai viet trinh b[.]
VE HE THONG NANG LUG DAY HOC CUA NHA GIAO TRONG CAC CO S d GIAO DUG NGHE NGHIEP theo tiep can ndng tuc thuc hien TS.VuXuanHCing Vien trudng Vien Nghien cdu Khoa hoc day nghe r Tom t5t Bai viet trinh bay nhufng nghien cijfu ve he thong nang lUc day hpc cua nha giao giao due nghe nghiep theo tiep can nang liic thUc hien Qua viec phan tich nghe, phan tfch cong vi&c, toan bo cau true, n6i dung cua nang lUc day hoc da difoc lam ro gom: Nang lac thiet ke day hoc, nang lUc tien hanh day hpc, nang lUc kiem tra, danh gia day hpc va nang li/c quSn \y day hpc He thong nang luc day hoc la ca s6 quan trpng de thiet ke, xay dung cac npi dung dao tao nha giao giao due nghe nghiep hi^n nay, dap ifng yeu cau hpi nhap cang sau rSng THkhoa: Nang luc thUc hien, nang li/c day hgc, nhd gido gido due nghe nghiep Abstract ' ! The paper presents the study of the system's competences of vocational education teachers according approaching the competence Through the analysis of occupations, job analysis, the entire structure and contents of the teaching competence have been clarified include: teaching design competence; teaching competence; test and evaluation teaching competence and teaching management competence The system of teaching competence is an important content for the design and construction of teacher training content current vocational education, to meet the requirements of deeper integration V Keywords: competence, teaching competence, teaching, vocational education teacher Nha giao noi chung, nha giao giao due lac thac hien {NLTH), nang lac day hpc eua nghe nghiep (GDNN) noi rieng co vai tro quan nha g i i o GDNN trd chu^n dau ra, trpng phat trien nhan liic lao dpng ky tieu ehi de xay diing va danh gia cae nang liic thuat true tiep cho qu6c gia Nghj quyet Dai day hpc dao tao, boi duoing nghiep sU hpi dai bieu toan quoc lan thiJ XI cua D i n g pham Tuy nhien, hien eon nhieu quan da xac dinh phat trien dpi ngu giao vien la niem khac ve eau true, npi dung nang khau then chot de thi/c hien ddi mdi can bSn, liic day hpc cCia nha giao GDNN, dan den viec toan dien nen giao due Viet Nam theo hUdng xSy diing chiiOng trinh dao tao, b6i dJdng chuan hoa, hien dai hoa, xa hpi hoa, dan chCi nghiep vu sa pham eon dan t r i i , nang ve ly hoa va hpi nhap quoc te (1 ] thuyet, i n h hadng Idn den chat laang dao tao Nang liic day hpc la mot phan cCia dpi ngu nha giao GDNN,Tiep can NLTH hudng nang iJc sa pham va la nang liic quan trpng vao sa thiic hien thuc cac nhiem vu, nhat eua nha g i i o GDNN Theo tiep can nang cong viec day hpe cCia nha giao GDNN, ehfnh So 30 thang 3/2016 KHOA HOC D A Y NGHE [1] la mpt tiep can khoa hpc ve nang lac day hpc CLianh^ giio GDNN Quan niem ve nang life thiic hien "Nang lac thUc hien" la thuat nga dUpc djch tU tieng Anh {Competency hay Competence) hoac ti^ng OUc (Handlungskompetenz) dung cac tai lieu cua nhieu tac g l i trinh bay v^ quan di^m giao due, dao tao theo tiep can NLTH Theo nghTa thong thUdng, "competency" dupc nhieu tU dien Anh - Viet dieh la nang fue, kha nang Tuy nhien, nay, t h u i t ngiJ dUpc eac nha khoa hoe md rpng ndi h i m , khong dCfng d k h i nang cda eon ngudi ma la "cii l i m eho ngUdi co t h ^ lam dUOc cac cong viec cua nghe do" la "sa thac hien cdng cac cdng vigc cCia nghe"[5] phuong phap DACUM cho thay, nha giio GDNN CO nang liic ehinh: (1) Nang luc su pham; (2) Nang Igc chuyen mdn nghe va (3) Nang lue xa hpi Trong nang Igc su pham lai cd nang lUc chinh: (1) Nang lUe day hpc va (2) Nang Igc giao due [3] Nghien cCtu gan day ve NLTH cho thay: NLTH Saddl Cau triic NLTH Id kiin thUc, ky nang, thdi can thiet, duac kit hap nhudn nhuyen, khdng tach rdi dethuc Men Nang luc day hpc la mdt hai duac cdc nhiim vu, cdng viec cu the cua mdt nghe phan eua nang Igc su pham v i dupe bieu hien theo chuan dgt ra, nhCfng dieu kiin nhdt cu the qua nang Igc phan la: Nang lUc dinh Cic t h i n h to cua NLTH bao gom: Kien thiet ke day hpc; nang Igc ti^n hanh day hpc, thUc, ky nang, t h i i dd; chuan d i n h g i i va dieu nang lUc kiem tra, danh gia va nang lUc quin ki$n de thiic hi&n cdng viec dd [3]{Sc/d6 1) ly day hpc (Se/dS2) Qua p h i n tfch ngh6, phin Tiep ein NLTH dao tao nha giao GDNN tich edng viec edn cho thay, moi nhom 1^ xem xit cic nhiem vu, cdng viec eCia n g h i nang lUc lai ed nhieu nang Igc thinh phan khic day hpc mot chinh t h l thdng nhat cua 2.1 Ndng Ivfc thi^t kedqy hoc NLTH, tich hop giaa kien thCfc, ky ning va thai Thiet k^ day hpc l i cdng vi§c quan trpng dp de n h i giao GDNN cd the hoan dUOc eua ngudi giao vien hoat dpng day hpe nhiem vu day hpc cCia minh Nhi giio thac hien Ning lUe thiet ke day hpc dUOc the hien qua dupc cic nhi^m vu, cdng viec cua nghe day hpc mdt sd nang Igc eu the sau; theo chuan dat ra, cd nghia la hp cd nang liic thuc hi^n Nhiem vu, cdng viec cCia nghe day hpc cung chfnh ia cac nang lac day hpc cua nha giao GDNN Nang lUc day hoc cua nha giao GDNN theo tiep cdn NLTH Cd nhieu nghien eUu ve n i n g Igc day hpc cua giao vien Co ket qua dUa nang lUc [6], cd nghien cOfu dUa nang lue [7] Theo ket qua nghien cUu tU viec phan tich nghe theo Sa Nang life day hpc ctta nha giao GDNN [2] KHOA HOC D A Y NGHE SO 30 thing 3/2016 a) Nang lUc chuan bi thiit ki bai hoc De cd the ehua'n bi thiet ke day hoc duqc tot, do: hdi ngudi giao vien phai ed nang lUc hieu hpc sinh Idp daoc phan cdng giang day; nang Igc nghien eUu chuong trinh, ke hoach dao tao; xac djnh dMc ky nang day hpc (npi dung day hpe}; nang lUc thu thap giao trinh, tai lieu; nang lUe nghien cUu tai lieu Trong nhieu nang lUc ke tren, nang lUc hiiu biit doi tuang (nang lUc hiiu hoc sinh tdp duac phan cdng day) la mdt nhCfng nang Igc quan trpng cua nang Igc chuan bi * Ndng lUc viit muc tieu day hoc Trong thuc te, cd nhieu giao vien rat mudn day that tdt, nhutig ho khdng cdy tadng rd ring ve cai dfch cuoi cung phai dat dUdc sau bai day nen den cudi buoi hoe, ed nhieu hpe sinh thac hien dupc, cd mdt so hoc sinh thi khdng, dieu chinh la phu thudc vao nang luc viit muc tieu bdi hoc cua ho Muc tieu day hpc la tuyen bd ve nhdng gi hpc sinh phai hieu rd, phii lam duac sau bai hoe, * Nang iQc xac dinh hogt dgng day hgc thiet ke day hpc Nang lUc the hien sg xac djnh kha nang nam vOng nhQng kien thUc, ky nang, ky xao can cd trade lien quan den bai hpc d hoe sinh (de Iga chon hoat ddng hoc bade sau) Nhd cd nang lUe nay, ngUdi giao vien de dang xae dinh duac ky nang ky xio, thao ddng t i c mdi can huan luyen bai; Phan tfch dac diem hoat ddng cua Idp hoc de cd phuang an to chUc Idp; Phan tfch eac dieu kien thuc hanh hien ed de chuan bi phaong an to chdc Idp hoc hap ly; Xac dinh nhCfng hat nhan cho moi nhdm va each td chUc nhdm (neu cd thao luan hoic lam viec nhdm) Vi vay bieu hien trUdc het cua nang lUc hieu biet doi tUang la d cho, ngudi giao vien biet x i c djnh dugc khdi luang kien thUc da cd va mac do, pham vi ITnh hdi cua hoe sinh, td dd xac djnh mdc dp, khdi luang kien thdc, ky n i n g mdi can giiip hoc sinh ITnh hdi b) Nang luc thiit ki bai hoc Thiet ke bai hoc la mdt q u i trinh cd tinh he thong de bien eae nguyen tac day hpc ke hoach hoat ddng day, hoat dpng hpc va sd dung, khai thac phuong tien, tai lieu hoc tap Thiet ke bai hpc gan vdi viee viet muc tieu bai hpc, xac dinh ndi dung va hoat ddng day hpc, thiet ke cae tai lieu hoc tap Theo tiep can NLTH, nang lUc thiet ke bai hoc bao gdm cac td' Hoat ddng day v i hoat ddng hoc thdng nha't vdi cung mdt qua trinh va khdng hoat ddng nao thay the eho hoat ddng nao, Hoat ddng cua ngudi giao vien khdng cd muc dfch rieng cho minh ma nham muc dich tao hoat ddng nhan thdc tich cgc cua ngUdi hpc, Hoat dpng day hpc theo tiep can NLTH thudng bat dau t d hoat dong cua ngddi hoc, vay nang luc the hien d viee xac djnh iUGc nhdng hoat ddng eua ngudi hoe buoi hoc Xac dinh dupc cac hoat ddng ma hoc sinh phai tien hanh cung ddng nghTa vdi xac dinh phuong p h i p day hoc, vi mdi hoat ddng CLia hpc sinh can cd it nhat mdt hoat ddng tuang dng cua giao vien de hudng dan, to chdc, danh g l i eie hoat ddng dd * Mot so nang lUc khdc Ngoai cac nang Igc ca ban tren, de chuan bi tdt viee day hpc ddi hdi phai ed cie nang lUe khac nda nhU: Nang luc thu thap tai lieu; Nang lac dng dung edng nghe thdng tin v i o thiet ke bai hpc dien td; Nang Igc chuan bj dung, thiet bi day hpe; Ning Igc thiet ke, ehe tao dung day hpc dan gian v.v., 2.2 Ndng liic tien hdnh day hgc Dac diem noi bat cua ky thuat day hpc theo tiep can NLTH la ngUdi day td chdc va dieu So 30 thing 3/2016 KHOA HOC D A Y NGHE [3] khien hoat ddng eua ngudi hpc nham ITnh hdi kien thdc, ky nang, hinh thai dp nghe nghiep, chd khdng phai l i ap dat nhdng thd dd cho ngudi hoc Ning Igc tien hanh day hpc bao gom mdt sd n i n g lue t h i n h td sau: a) Ndng lUc sQ dung cdc phuang phdp day hgc phuang tien day hpc dd la: Dam b i o phuc vu thiet thgc cho b i i g i i n g ; Sd dung phu hap vdi die diem tam sinh ly cua hpe sinh; Sd dung dung Idc, dung each, du cudng dp; Dam bao cae quy tac dieu khien va van hanh; SU dung phai an toan, c) Ndng lUc tr'inh diin ky nang (thao tac mdu) Cie budc trinh dien ky nang bao gom: Moi mdt phuang p h i p day hoc, du truyen Budc T Chuan bi hanh ddng can l i m mau thdng hay hien dai, deu nhan manh len mdt Trong bUde n i y can cd sg p h i n tich hinh khi'a canh nao cua ca che day hpc hoic ddng can bleu dien eac dpng tic, cd nhan manh len mat nao thudc ve vai trd ddng ) Sap xep ehung trinh t g hop ly, cua ngddi day, Chinh vi the ma khdng cd mpt xac djnh cac yeu to khd, eie khau chuyen tiep, phuang phap giang day nao dupc eho la ly dg kien cae sai sdt cd the xay hpc sinh tudng, la tdi Uu nhat day hpc Mdi mdt luyen tap; Chuan bj c i c phuang tien, dung eu phuang phap deu cd uu diem cua nd Dieu can thiet tuang Ung; Djnh mdc thdi gian thgc quan cija nang Igc la ngudi day biet hien v i dg kien nhdng g i i i thich kem theo; Du khai thac, van dgng, sddgng mot cich tdi Uu, hieu q u i eie phuang p h i p dieu kien ed the Phuong phap day hoc truyen thdng phai daoc ket hap vdi cic phuang p h i p day hoc hien dai de p h i t huy tinh tich cgc cua ngUdi hoc kien vi tri va cae dieu kien bieu dien de hoc sinh de quan sit Budc 2: Bieu didn h i n h ddng (hay ddng tic) mau Neu rd muc dfch cua h i n h ddng, trinh td thao ddng t i c v i yeu eau kem theo, ket qua Nhu vay, nang igc ddi hdi giao vien phai biet van dung phuong p h i p day hpe mdt each sang tao vao cic ndi dung b i i giang cu the b) Nang luc sQ dung phUong tiin day hoc, thiit bl thuc hanh can dat &uac (ed the dung phim, i n h minh hpa), sau dd thgc hien: (a) Bieu dien hanh ddng mau vdi tdc dp binh thudng dieu kien tieu chuan; (b) Bieu dien h i n h ddng mau vdi tdc dd cham, the hien rd tdng ddng tic, cd ddng, eie khiu Giao vien phai cd nang lUc sd dung thiet bi chuyen tiep giup hpc sinh quan sit ghi nhd va phuang tien day hoe, biet dua md hlnh, hoe tdng dpng tic, cd ddng mdt each chfnh xic; cu cho ngUdi hoc quan sat dung liic, de t i p (e) Bieu dien lai v i i lan cic dpng t i e phdc tap trung sg chu y cua ngudi hoe Neu khai thie ket hop vdi viec giai thich b i n g ldi v i chi dupc cae phuang tien day hoc, thiet bj thUe cic sai sdt thddng gap thdc hien ehung; hanh se giup cho ngddi hpc tiep can vdi thUe (d) Bieu dien tdm t i t lai toan bd hanh ddng te, giao vien dd vat v i gid len Idp, gid mau vdi tdc dp binh thudng de hoe sinh co giang se trd nen hap dan, ngudi hpc chu y vao duac bieu tupng ve tien trinh cie edng viec npi dung bai giang, hieu qua gid giang se tang len rd r^t Nguyen t k chung khai thac vasd dung Budc 3: D i n h g i i ket qua bieu dien bang cich yeu cau mdt vai hoe sinh bieu dien lai hanh ddng m i g i i o vien vda the hien de xae [4] KHOA HOC D A Y NGHE SO 30 thing 3/2016 djnh mdc dd nam vdng ddng t i e m i u va tien f/jdc;Ngdn n g d g i i n dj, sinh ddng, g i i u hinh trinh edng viee anh, cd ngd dieu, sing sua, bieu cam vdi cich d) Nang li/c td chQc hgc tap theo nhdm phat am mach lac dd khdng ed nhdng Day hoc theo nhdm vda l i mdt hinh thdc sai pham ve tu t d hpc, ve ngQ p h i p , ve ngQ day hpe vda la mdt phuong phap day hoe am Hlnh thdc trinh bay eho de hieu, cd tich cUc dang duac sd dyng phd bien vi tinh chieu sau ve tU tUdng, cd sdc lay ddng tam Uu viet cua nd ca ve mat xa hdi va ve giao hdn ngudi hpc due Tuy nhien, muon day hpe tuang t i c theo e) Nang lUc xQly tinh huong suphgm nhdm cd ket qua, ngUdi g i i o vien can cd Tinh hudng sdpham la hien tuang, sg viec cic NLTH sau day: a) Ndng lUc chuan bi: Ddi xay qua trinh giao dgc m i giao vien hdi g i i o vien phai cd cd kha nang chuan bi phai giai quyet Trong thUc te day hoe cd rat npi dung, ve phuang p h i p day hpc, chuan nhieu loai tinh hudng su pham xay nhU: (a) bi tai lieu, phuong tien, thiet bi luyen t i p , Cac tinh hudng ve kien thdc, ky nang; (b) Cae vj tri luyen tap v.v , de d i m b i o eho hoat tinh hudng ve t u t h e , t i c phong, trang phuc dpng nhdm dUOc thuc hien ed hieu q u i ; b) cua giio vien n h u g i i o vien; (c) Cae tinh hudng Nang luc to chdc, quan ly: Ddi hdi giao vien ve each Qng xd cCia hoe sinh phai biet thu thuat chia nhdm theo yeu eau Hoat ddng day hoc va g i i o due ludn dien cOa b i i hoc v i mue dich day hpc cCia minh, het sdc phdc tap, da dang, vi v i y ddi hdi ngudi Theo ddi hoat ddng eua eae nhdm (ghi bien giao vien p h i i cd nang Igc kiem soit, q u i n ly, ban, ghi chep, theo ddi, ), gpi y kip thdi cac d u kien v i g i i i quyet tdt eie tinh hudng sU VUdng mac cua cac nhdm, pham n i y sinh, dap Qng duoe yeu cau cOa day d) Nang luc giao tiip, sQ dung ngdn ngQ Ngdn ngQ la phuang tien giao tiep cua hpc va giQ dUOc uy tfn cho giao vien 2.3 Nang luc kiem tra, danh gid day hgc ngudi giio vien Ngudi g i i o vien cd ngdn ngd Nang Igc ddi hdi viec kiem tra, d i n h rd rang, dien c i m se giup eho ngddi hpc hieu g i i p h i i dam bao tfnh k h i c h quan, edng bai tdt hon, ngudi hpc se tap trung chu y bang va chuan xic Lamduac nhu the thi uy gid giing Ngdn ngd cdn la yeu tdcua tai nang tin cua ngUdi giao vien se dupe tang len, tao su pham, nhieu nha giio GDNN nhd cd k h i dupe mem tin eua ngudi hoc Ngoai viec nang dien dat tdt ma lam cho ngudi hoe de tiep danh gia ket q u i hoc tap eua hoe sinh ngudi thu bai giang giao vien p h i i biet t U d i n h g i i nhQng Nang luc giao tiep va sd dung ngdn ngd la nang luc bieu dat rd r i n g , mach lac y nghT edng, han che cua tQng bai g i i n g de ed bien p h i p khac phuc, v i tinh c i m cua minh b i n g Idi ndi cung nhu De d i n h g i i ket q u i hpc tap cOa ngudi net m i t , cd chf, dieu bp N i n g Igc ddi hdi hpc dupc khich quan, cdng bang va chuan g i i o vien p h i i chu y den c i ndi dung va hinh xac, ddi hdi giao vien phai ed nang Igc bien thdc bieu dat, eg the: (a) Ve ndi dung: Ngdn soan cdng cu d i n h gia, nang igc sd dung ngd phai ehda ddng mat dd thdng tin Idn, cic cdng cu danh gia, nang luc phan tich cie dien ta, trinh bay p h i i ehfnh xic, cd dpng, minh chdng d i n h gli, van dung thao sue tich Ldi ndi p h i i phan i n h duac tfnh va linh hoat cic phuang phap va ky thuat ke tue, dam bao thdng tin logic; (b) Vi hinh kiem tra, d i n h g i i theo tiep can NLTH 56 30 thing 3/2016 KHOA HOC D A Y NGHE [5] Nhu vay, theo tiep can NLTH, thdng qua 1^ A-i\ liyr J viec phan tfch nghe, phan tfch cdng viec theo / % ; , / , A < , i * r < ' i « H ^' ' L j day hpc cCia nha giao GDNN da duac xic djnh rd ca ve cau true, ndi dung, the hien tinh khoa N, ,h,;,U.I.,sl,o ' M — ,.,.,lmi,L.,.hw»«,Js,l M.tol'-^ ' i M,.l„,r,„ ! .\l li^n liiinh tUfy ll,.n , | Nl MI iKinj; phinmg pliiip Ji.iv hw | -•H M inl(iiiy phuong iKii i.la> IK," ^ilm^ãll^ntoôml lUc day hpc cua nha giao GDNN la sg phan anh toan bd eie nhiem vu, cdng viec day hoe hang cua nha giao GDNN mdt he thdng thdng nhat, chat che, logic Day se la -^ ^ hoc v i thue tien cao (so 3) He thdng ning ^7T,^„,-,;i„d.„"h„ • J phuang p h i p DACUM, he thdng nang lUc ok6,l.„l,„ ca sd quan trpng de thiet ke, xay dung eie ndi dung dao tao, boi dUdng nha giio GDNN, ] hudng tdi sg thuc hien thao eac edng H -• — • * • —»-; \ l pnti iio|i, su dyng iiyi'iii ngu ! viec cua n g h e a L^ | NI.M,lv-,n;,l,iM„B.„|J„m Td; lieu tham khao - ? V/, Ui'i IF., danh i;ia | -H NM„;„ I M ,„,to8c4,„„,d.i„l,p Vi |.l,.-,„ ,.ch > ~™l, clum.a - ^ J „ » , J „l,,, J V, , „ „ ( , , / „ j ; , « ' —1 M l,,|, kO l.o,.cl, Jjy lijc - ] \ I6dmgil5> h * : ~.-| - ^ J I.Dang Cong sinViet Nam (2011),Van kien Dai hdi dai bieu toan qudc lan thd XI cua Dang, Nxb Chfnh tr; qudc gia, Ha Ndi; Meier Bernd, Nguyen Van Cddng (2009), Bai giang Ly luan day hgc hi^n dgi TrUdng Dai hpc Potsdam, DHSP Ha Ndi | Vu Xuan Hung (2012),^Day hoc hien dgi va Nl dl^il khicil qil^i irinll J,i> liyc | ndng cao nang iQc day hoc cho gido vien, Nxb N : HrkKiii Ir.iikiilh!;)ii1tnicl,iv-ii | Lao ddng • Xa hdi H i Ndi Sa He ihdng nang luc day hoc cv the cua nha gido GDNN 2.4 Ndng Idc quan 1^ day hoc Nang luc quan ly day hoc the hien d viec ngudi giio vien phii biet thu t h i p thdng tin de lap cac ke hoach, lich trinh, thdi gian bieu cho cho hoat ddng day hpc (lap ke hoach); biet huy ddng, phan phdi, td chdc cic ngudn lUc, quan ly Idp hpc de thuc hien tdt eae hoat ddng day hoc (td chdc thdc hien); hddng dan, dieu hanh cdng viec hpe tap Idp, nhdm, dam bao tien trinh v i thdi gian day hoc de viee day hpe dat mue tieu day hpc da de (chi dao,,dieu khien) Mat khic, phai biet tg kiem tra, danh gia riit kinh nghiem eho viee day hpc cua minh Gerhard Steindof(1995), Grundbegr/ffe des Lehrens undLernens, Auflage, Julius Klinkhardt Veriag, RudolfTippelt (2003), Competency - based training, Larissa Weigel, Heidelberg, Germany Standards for Teacher Competence in Educational Assessment of Students (2016); http://buro5.org/standards-teaeher-competence -educational-assessment-students Teaching competence (2015); Website http://youremployment,biz/competency/ teaching-competency/ University of Vi/est Georgia (2008), Seven Principles of Good Teaching Practice http://w/ww/ v/estga.edu/~distance/webct/facultymanual/ AfacCommun.html [6] KHOA HOC D A Y NGHE Sd 30 thing 3/2016 ... tra, d i n h g i i theo tiep can NLTH 56 30 thing 3/2016 KHOA HOC D A Y NGHE [5] Nhu vay, theo tiep can NLTH, thdng qua 1^ A-i\ liyr J viec phan tfch nghe, phan tfch cdng viec theo / % ; , / ,... sau; theo chuan dat ra, cd nghia la hp cd nang liic thuc hi^n Nhiem vu, cdng viec cCia nghe day hpc cung chfnh ia cac nang lac day hpc cua nha giao GDNN Nang lUc day hoc cua nha giao GDNN theo. .. cua giao vien Co ket qua dUa nang lUc [6], cd nghien cOfu dUa nang lue [7] Theo ket qua nghien cUu tU viec phan tich nghe theo Sa Nang life day hpc ctta nha giao GDNN [2] KHOA HOC D A Y NGHE SO