Students learned a useful physics lesson after successfully launching hundreds of water-bottle rockets they designed over the weekend. The water rocket propulsion competition at King George V School in Kowloon saw 400 primary and secondary school students take part. The event was part of the 'Energy for Learning - Flight of Hope' programme organised by the Boys' and Girls' Clubs Association of Hong Kong and the Hong Kong Aerospace Society. It was sponsored by Chevron Hong Kong. The three-month programme includes workshops and lectures to promote students' interest and creativity in science and technology. The aim of the rocket competition, held on Sunday, was to use plastic water bottles to create rockets and see which could travel the furthest. The students designed the shape and size of the wings attached to the bottles to achieve this. The winner was Ripa Tso Hoi-ching, 13, from Our Lady's College. Her rocket flew 71 metres thanks to a little water and some air to create the pressure it needed to fly. Ripa credited her success to the stable wings she built. Other competitions included another rocket-building contest which was won by a solar-powered effort from Michael Li Kin-pong of CCC Tam Lee Lai Fun Memorial Secondary School, and a drawing competition which was won by Jenny Tang Sui-yin, 13, from New Territories Heung Yee Kuk Yuen Long District Secondary School. Her artwork was based on the intangible nature of dreams. Jocelyn is a Young Post intern