THE first 15 years have seen St Teresa Secondary School grow into a mature, full-fledged school. This was the observation of the school supervisor Sister Esther Ling, who was speaking at the school's 15th graduation ceremony. ''Fifteen years is a comparatively short period, but in that time St Teresa had developed fast, thanks to the fine leadership of the principal and the co-operation of teachers, parents and students, a sound foundation had been laid for the students,'' she said. In her annual report, the principal Ms Hilda Kwan said that St Teresa's had worked hard to give its students an all-round education. The children have been guided carefully in their moral, intellectual and physical growth, with much emphasis given to individual and social development. An understanding of Chinese culture has been an important aspect of the school's education, Ms Kwan added. Of the Form 7 graduates, six of the 16 science students gained admission to the University of Hongkong last September. Sixty per cent are furthering their studies in tertiary institutes. Of the Form 5 graduates, 80 per cent were continuing their studies. In order to encourage students to work harder, the school introduced an ''improved student'' scheme last year. The programme has benefited the students to a marked degree, producing better academic as well as sports results. The principal thanked the staff and students for their hard work, particularly for their contribution towards the creation of the new school extension. With the extension, the floating class system could be discontinued, thus giving the students a betterlearning environment, the principal said. The guest of honour, Ms Wong Leung Kam-shan, Deputy Regional Commander, Kowloon West, Royal Hongkong Police Force, praised the students for their academic achievements and commended the school for providing varied extra-curricular activities and stressing the importance of moral education. In a society like Hongkong, where there are equal job opportunities for both sexes, young people should also be ready to face the numerous challenges, Ms Wong said. A cake to mark the school's 15th ''birthday'' was brought on stage and ceremonially cut by school officials and the chief guest. The ceremony ended with a performance by the school choir.