HOW does a triangle relate to the inter-relationship of teachers, parents and children? This was the metaphor adopted by Dr Shen Suet-ming when she delivered a speech during the fifth anniversary celebration of the Parents-Teachers' Association of Belilios Public School. Dr Shen, who is currently researching the co-operation between parents and teachers, suggested that a well-formed triangle closely resembled the relationship among the three parties. Not only could a golden triangle be developed when the relationship amongst the three was harmonious and amicable, but it would also give out light and shine brilliantly, she explained. ''Secondary students are not little children. They have their own thoughts and they are independent. However, they still need their parents' care and their teachers' guidance,'' said Dr Shen. Both parents and teachers must co-operate effectively to ensure the healthy development of the students. Dr Shen said students' worries, though sometimes seeming trivial to adults, could have a significant and long-lasting influence on them. However, apart from problems related to money, students tend to solve their concerns, such as those relating to emotions and behaviour by themselves or through sharing with friends. ''There is such a close relationship between parents and children. So how come children head for their friends when they are in trouble?'' ''Teachers are the ones who teach and guide students. Why don't students go to their teachers when they have worries?'' asked Dr Shen. In order to form a golden triangle, parents and teachers must try to understand that young people are facing a lot of changes and sometimes need help to alleviate their anxieties. Hundreds of parents and students joined the PTA's fifth anniversary celebration, especially thanking parents who have played such a supportive role in the association. After a ribbon-cutting ceremony and speeches by Wan Ping-pui, the chairman of the association and Dr Shen, an entertaining variety show was performed by staff, teachers and students, and game stalls were set up.