Graduate Program in Secondary School Science and Mathematics Education.Karagöz Akar, Gülseren.Saraç, Merve.2023-03-162023-03-162016.SCED 2016 S37https://digitalarchive.library.bogazici.edu.tr/handle/123456789/15568In thisstudy,Iarticulatehowaprospectivesecondarymathematicsteacher reconstructs complexnumbersuponthesetofrealnumbersinthecontextofthe solution setsofquadraticequations.Previousresearchhasindicatedthatonceasked the meaningof x and y in theCartesianformofacomplexnumberwhichisformally de ned as x + iy where x and y are realnumbers,bothstudentsandteacherswere able tostatethat x and y are realnumbers,yetconsideredthemseparatelyrather than beingcomponentsofasingleentity.Thus,thequestionarisesastowhat x and y refer toalgebraicallyandgeometrically;why x and y havetoberealnumbersand what itmeanstobeanelementofthesetofcomplexnumbers.Thisstudyexplicates a prospectivesecondarymathematicsteacher'sanswerstothesequestionsthroughthe articulation oftheparticipant'squantitativereasoningbyconsideringSfard's(1991) theory onthedualnatureofthemathematicalconceptions.Withthisaccount,Iintend to contributetomathematicseducationbyprovidingevidenceonhowthedevelopment of theelementsofcomplexnumbers,whichisthroughshrinking/stretchingofthe distance(s) betweentherootsandthex-coordinateofthevertexofanyquadratic functions' graph,a ordsconceptualizinganycomplexnumberasasingleentityina well-de nedsetratherthanonlyanalgebraicprescriptionofcertainoperations.As the resultoftheinstructionalsequenceinthisstudy,theparticipantpresentsthiswell- de ned setasthesetconsistingoftherootsofquadraticequationswithrealcoe cients.30 cm.Mathematics teachers.Numbers, Complex -- Study and teaching (Secondary)xviii, 151 leaves ;