'SMILE, SMILE,' the photographer keeps reminding Louise Kwan Wai-fong, who is a little tense in front of the camera.
But as soon as the principal is asked to sit in front of the mural painted by her students at Pelletier School, a smile appears spontaneously.
Her students used to spell trouble for other teachers. They were girls who had dropped out of school because of family, emotional or behavioural problems.
But at Pelletier, a special school in Ngau Chi Wan focusing on students' social development, lives have been transformed. For almost 25 years, Ms Kwan, 48, has been part of the process. She joined the school as a graduate from the Grantham College of Education.
'I first came across special education in the second year at Grantham,' she recalls. 'It was not considered important, so there were only two sessions about it in two years.
'When I heard the term 'maladjusted', I was curious. After learning what it meant, I thought that would be the way to go.'
Lecturers, classmates and friends tried to talk her out of venturing into the field. But she turned down offers from grammar schools and got an interview at Pelletier.
'The principal told me I was too young and inexperienced. She was worried that I would have a hard time because many young teachers were often reduced to tears.
'I said: 'I am young but I am mature. I also have the qualities this job requires - a caring heart and passion.
If age is such a problem, I will come back in a few years' time.' '
Ms Kwan's fighting spirit to overcome challenges was developed at a young age.
Upon finishing primary school, her parents decided she should start working despite the fact that the Government had waived her secondary school tuition fees because of good results.
She did not eat for three days. Neighbours and relatives eventually managed to persuade her parents to let her continue studying.
However, she had no financial support from her parents and had to do part-time jobs making paper bags, doll clothes and handkerchieves.
'When I got better at it I was able to study as I worked. Later my mother would leave some money for me on the table every now and then. So in a way they did support me,' she says.
Looking back, Ms Kwan dismisses it as 'a minor interlude'. Her job and students are more important now.
'No matter how bad a person is, there is always something good in them. Nobody is born [bad],' she says. 'Some may refuse to change despite all your efforts. There were times I cried with students during long discussions. But all of a sudden something would trigger a change.'
She considers her job a blessing because it has been a dream come true, and it still inspires her.
Students from diverse backgrounds bring new experiences. They have kept her hopes high during difficult times.
Most of all, they constantly remind her of the value of life.
Ms Kwan says: 'The founder of the school once said: 'A soul is more valuable than the whole world.' Many students have asked me if they are really worth that much. I tell them: 'Your lives are not cheap.' '