Kung fu master Ha Tak-kin clears his throat, his voice drowned out by the clashing of cymbals and beating of large drums.
Raising his pitch, the fit 40-year-old embarks on what has become a routine in his life - teaching youngsters the basics of a traditional art form - the lion dance.
Scores of 15 and 16-year-olds in the school yard listen attentively as he explains the skills involved.
A short distance away, other youngsters practise playing the musical instruments that accompany the dance.
Chu Shek Lun Pre-vocational School is the latest to join more than 80 others arranging for their students to learn an art dating back centuries.
Lion dancing may be a regular feature of festive occasions, especially during the Lunar New Year, but there are only a few who share Mr Ha's passion and commitment.
Faced with a heavy workload and economic pressures, fewer adults are learning it these days.