More than a year before a student plunged to his death during morning assembly at his Tung Chung school, a teacher heard him pondering how long it would take to hit the ground as he stood on the seventh floor. Teachers described the incident yesterday as they testified at the inquest of Wong Ling-fung, 17, a Form Four student at Tung Chung Catholic School. Wong was diagnosed with psychosis, but teachers described a quiet and well-behaved student. He died after plunging down to an outdoor playground at the school on May 24 last year as his schoolmates and teachers were gathering for morning assembly. Teachers yesterday recalled a day in 2008 when Wong was found holding onto a railing on the seventh floor of the school after a Chinese speech practice. 'He wouldn't leave,' said teacher Ng Sau-man, who had been helping him practise for a forthcoming speech competition. 'He went to the rail and held on. He said, 'It would take seven seconds to reach the bottom from here'.' Worried teachers arranged for a school counsellor to speak to him and eventually he was taken to a hospital, the hearing was told. Testifying yesterday, Wong's mother, Yip Wai-kuen, said he was diagnosed as being in the early stages of psychosis and was placed on medication. Witnesses said that weeks before Wong died, he broadcast a video clip in which he insulted students and teachers, singling out teacher Chan Sau-fong who taught him Chinese. The video exercise was meant as a chance for students to express their appreciation of their teachers. Wong's father, Wong Yeung-chiu, said the school recorded a demerit against his son and demanded an apology. Under cross-examination by Albert Ho Chun-yan, representing Wong's family, another teacher, Lam Sik-wing, said Wong was put in a room every day for six days to reflect on what he had done. This led his parents to raise questions during the inquest. 'Even after he apologised, they would not let him go on a school trip,' the father said. 'He was trapped in a classroom. These teachers, how could they treat my son like this?' The mother said: 'My son needed to be watched with a lot of care.' The father also said the school instructed the teenager to take his medicine in a teacher's presence at school from then on. Teachers said that the day Wong died had been the first time he had brought medicine to school and taken it under supervision. Chan, the teacher targeted in the video, said she was never angry with the student. She read out a letter she received from Wong in which he apologised. The inquest continues before Coroner Michael Chan Pik-kiu.