Literature Review on Blended LearningLiu+Chunmei+Indika+Liyanage【Abstract】Althoughverybrief，thisreviewoftheresearchthathasbeencarriedoutoverthepast15yearsonblendedlearningshowshowthefieldhasevolvedfromcontroversialstudiesofthedefinitionstoempiricalstudiesofitsteachingeffects.Inthisarticle，Ipresentthebirthandriseofblendedlearninganddescribedthreepartiallyoverlappingcategoriesofthestudiesonit.【Keywords】BlendedLearning；EducationalTechnology；BlendedApproachTheterm“blendedlearninghasbeenaroundforoverfiftyyears.Itbecamepopularwiththeriseofcomputersandtelecommunicationsthatenabledremoteanddistancelearning.Althoughtheconceptsbehindblendedlearningfirstdevelopedinthe1960s，theformalterminologytodescribeitdidnottakeitscurrentformuntilthelate1990s.Oneoftheearliestusesofthetermappearsina1999pressrelease，whichmentionedthat“TheCompanycurrentlyoperates220on-linecourses，butwillbeginofferingitsInternetcoursewareusingthecompanysBlendedLearningmethodology.Theterm“blendedlearningwasinitiallyvague，includingawidevarietyoftechnologiesandteachingmethodsindifferentcombinations.In2020，thetermbecamemoreconcretewiththepublicationofthefirstHandbookofBlendedLearningbyBonkandGraham.Grahamdefined“blendedlearningsystemsaslearningsystemsthat“combineface-to-faceinstructionwithcomputermediatedinstruction.BonkandGraham，2020BlendedlearningoriginatedinprofessionaldevelopmentandtraininginBusinessindustrySharmaandBarrett，2020wasthenappliedinhighereducationMacDonald，2020.AndfinallyitwasemployedinEnglishlanguageteachingELTandgraduallybecameacommonplaceinELTTomlinsonandWhittaker，2020.Threepartiallyoverlappingcategoriescanbedistinguishedwithinblendedlearningresearch.Thefirstcategoryofblendedlearningstudiesconsistsinanalysisofthedefinitionsofblendedlearning.Thesecondgroupofblendedlearningstudiesfocusesonthecomparativeresearchontheeffectivenessofblendedlearningandconventionalclassroomapproach.Thethirdbodyofblendedlearningresearchcentersonpedagogicalreformbyredesigningtheblendingway.I.LackofConsensusonaDefinitionofBlendedLearningTheliteratureoffersmanydifferentpracticaldefinitionsofblendedlearningBliuc，Goodyear，Ellis，2020.AccordingtoVanDerLinden2020，“blendedlearningisbroadlydefinedasreplacingseattimeincourseswithonlineactivitiestoachievelearningobjectives.Whethertermedhybridorblended，akeyfeatureofthismodeofinstructionisthatitrequiresafundamentalcourseredesignthattransformsthestructureandapproachtostudentlearningGarrisonVaughan，2020.TangJingwei2020introducedthedifferentscholarsdefinitionsofblendedlearningandpointedoutthatuntilnow，theresnoconsensusonhowitisdefinedanddifferenttermssuchas“blended，“mixed-modeand“hybrid，areused.TANGlistedthreetypicaldefinitionsbysomeresearcherssuchasDziuban，HartmanandMoskal2020，KekangHe2020andJiahouLi2020.Tangfinallysummarizedtheblendedlearninginhisstudyas“anoptimizationcombinationwhichaimstoincludethepositiveaspectsofface-to-facelearningandonlinelearning.Wasoh2020listedthetwodescriptionsofblendedlearningaccordingtoRoviaandJordan2020，ColisandMoonen2020.ColisandMoonenstatedintheirstudy“blendedlearningisahybridoftraditionalface-to-faceandonlinelearningsothatinstructionoccursbothintheclassroomandonline.MajaGrGurovi?2020madeabriefliteraturereviewofthedifferentdefinitionsofblendedlearning.HecitedThornesdefinitionofblendedlearningThorne，2020“blendsonlinelearningwithmoretraditionalmethodsoflearninganddevelopment.Majadefinedblendedlearninginhisstudyasface-to-faceteachingandlearningsupplementedbyanonlineCALLcomponentdeliveredthroughalearningmanagementsystemLMS.KevinLothridge2020andhisco-researchersgaveashortdefinition“blendedlearningisusingtwoormoreinstructionaldeliverymethodstoimpartknowledgeandskillstothelearner.AccordingtoSoandBrush2020，“Generally，blendedlearningmeansanycombinationoflearningdeliverymethods，includingmostoftenface-to-faceinstructionwithasynchronousand/orsynchronouscomputertechnologies.TheyagreedwithPhippsMerisotis1999thatblendedlearningisthe“thirdgenerationofdistanceeducationsystems，whichischaracterizedasmaximizingthebestadvantagesofface-to-facelearningandmultipletechnologiestodeliverlearning.VanDerLinden2020pointedoutthatmostcollegesanduniversitiesfailtodefineblendedlearningataninstitutionallevelandtheabsenceofaprecisedefinitionthenlendsitselftoblendedlearningbecomingameredescriptionofasingularcourseratherthananinstitutionalstrategy.II.ComparativeResearchonEffectivenessofBlendedLearningandConventionalClassroomApproachPreviousstudiescomparingtheeffectivenessofblendedlearningandconventionalclassroomapproachhavereportedhigherachievementandattitudelevelsamonginstructorsandstudentsThang，Wong，Noor，2020.Wasoh2020summarizedtheadvantagesanddisadvantagesofblendedlearningbyreviewingtherelatedliteratures.Someoftheadvantagesofblendedlearningincludecost-effectivenessforbothlearnersandtheinstitution.Someofthedisadvantagesmayincludecomputerandinternetaccessibility，limitedknowledgeintheuseoftechnology，andlackofcomputerlabsonuniversitycampus.Lothridg