A 17-YEAR-OLD schoolgirl fell 17 floors to her death early yesterday, hours before she was due to meet her teacher for counselling. Lam Lai-chuk was found unconscious outside Ching Mui House, Cheung Ching Estate on Tsing Yi Island, at about 5.40 am. She was dead by the time she reached Princess Margaret Hospital. Police found a note on her bed, saying she wanted ''to leave the world early''. Principal of her school, Mr Kwok Man-leung, said he had been told by the family that the girl was unhappy with a recent mock examination. He said: ''We are very surprised, but she appeared to be unhappy earlier this week when the teachers distributed the marked mock exam papers. ''We had planned to have a counselling session this morning so she could talk face-to-face with her class teacher before next month's Hongkong Certificate Examination.'' Mr Kwok said Lai-chuk's conduct was good in school and her academic results were average.