Mrs Pienaar qualified as a History and Geography teacher at the University of Stellenbosch in 1975. She started her teaching career at the Waldorf School in Constantia, Cape Town in 1976, where she taught Afrikaans in the senior phase. In 1979 she was appointed by the Cape Education Department as a teacher at the Boys Reformatory in Constantia. She gained invaluable experience at this institution, teaching young boys under the age of 18 who were sentenced by the court to attend the reformatory. In 1993 she resigned in order spend more time raising her three young children.
In 1996 she returned to teaching as a part-time teacher at Norman Henshilwood, specializing in History. In 2001 she accepted a permanent post at Norman Henshilwood and became Subject Head of History in 2004 and was appointed Head of Department soon thereafter. In 2004 she joined the Senior Leadership Team of the school. Mrs Pienaar is a matric marker of History.