Rua Isobel Gardner was born at Devonport, Auckland, on 13 March 1901, the child of Scottish parents Agnes Dawson Neilson Rankin and her husband, Robert Gardner, a banker. She attended Auckland Girls’ Grammar School (1915–19), where she excelled as a scholar and sportswoman. The family moved to Wellington soon after Rua finished her secondary schooling and she enrolled at Victoria University College. She graduated MA in 1924 and completed her DipEd the following year. She gained university blues in tennis and basketball and represented Wellington in both these sports.
By her own admission Gardner drifted into teaching, ‘because there wasn’t anything else to do’. She began her career at Wellington East Girls’ College in 1925 and remained there for 19 years. During this period she taught English and history and led the school’s debating team.
In 1944 Gardner became the fifth headmistress of Auckland Girls’ Grammar School. During the 22 years she held the position, this short, plump, vivacious teacher with a zest for life gained a reputation for courage and outspokenness. Her annual prize-giving addresses often stressed the need for girls to have as good an education as their brothers to ‘give them a dowry for their marriage and an insurance policy for their future’. For this to be achieved, adequate facilities were required and she battled to ensure these were provided. In 1945 she complained that girls’ schools were not given assembly halls with enough room for seating, which meant they had to go to boys’ schools or other halls for prize-giving ceremonies. Such inequality was not tolerated by Gardner, who claimed that the ‘ancients were more honest. In disgust they killed their daughters at birth. Aucklanders allow them to grow up if they can under vastly inferior conditions to those they give their sons and yet protest that they are just as fond of them as they are of their sons’. In her opinion, for girls to acquire a sound education they must have highly qualified teachers, stay at school for as long as possible, learn good work habits and be expected to maintain the same high standards of discipline at home as at school. She chastised parents for allowing their daughters to socialise with school-leavers, work during the term holidays or watch too much television.
Gardner was an innovative headmistress. During her tenure she formed a parent–teacher association, introduced athletic sports and started a students’ saving scheme. She appointed teachers in speech and drama, a fully trained nurse and a part-time Māori-language teacher. Gardner also became known as a sharp-tongued commentator on wider education issues. She condemned compulsory country service for teachers and complained about the low standards required for students to pass the Certificate of Education (a consolation prize for those who failed School Certificate but who gained 30 per cent in one or more subjects). She was an advocate for specialist secondary schools as an alternative to one school serving all children in an area; she believed parents had the right to choose which school their children should attend and was opposed to the rules governing zoning. She was keen to maintain high academic standards at Auckland Girls’ Grammar School by enrolling students from outlying suburbs who had particular reasons for wanting to attend, and also established an exchange scheme whereby students from Queen Victoria School for Māori Girls could complete sixth and seventh form at Auckland Girls’ Grammar. Gardner retired in 1966, though briefly took on a relieving position as principal of Solway College, Masterton, the following year. At the time of her retirement the Parent–Teacher Association established in her honour the Rua I. Gardner Scholarship Fund.
She was a long-serving executive member of the New Zealand Secondary Schools’ Association and was influential in persuading it to join with the New Zealand Technical School Teachers’ Association to form the New Zealand Post-primary Teachers’ Association. Gardner attended the council of the International Federation of University Women at Oslo in 1954, was on the board of the Auckland YWCA (1967–72) and on the Council of the University of Auckland (1968–72). In 1968 she was made an OBE for services to education. Rua Gardner died on 25 May 1972 at Orakei, Auckland. She had never married.