Yang Qi, a 13-year-old pupil who lives in a subdivided flat in Hong Kong with his parents, has spent years studying and playing on a piano that blocks part of the entrances to the kitchen and bathroom. He is among the pupils preparing for a charity concert in October at the Cultural Centre in Tsim Sha Tsui, which aims to raise funds to fight poverty, including by supporting children who lack the resources to develop their interests. Sze Lai-shan, deputy director of the Society for Community...