Bill Kwok Ka-yin, 16

Carmel Divine Grace Foundation Secondary School

The mobile phone. It is very convenient and lets us stay in touch with the world. Without mobile phones we would have to carry lots of change wherever we went.

Anfy Shum Yuen-wa, 16

St Catharine's School for Girls The electricity generator, as it allows us to run lights, computers and machines, which are all essential in everyday life.

Mandy Leung Man-chee, 17

Bishop Hall Jubilee School

The motor car, because it saves us having to walk everywhere and gives us time to do more meaningful things.

Jenny Leung Ching-yee, 15

St Catharine's School for Girls

Spectacles, because they give people back their good eyesight and are also great fashion accessories.

Esther Li Tsz-ling, 17

Good Hope School

The aeroplane, as it allows us to travel far in a short time. It also helps bring people together, physically and mentally.

Mandy Chu Ka-man, 17

SKH Bishop Mok Sau Tseng Secondary School

Chopsticks, because they are so convenient. They allow us to eat almost any food and also to make patterns on dumplings.

Carrie Kwok Chun-Wing, 17

St Rose of Lima's College

English, as it is a universal tongue and enhances communication between people. It also eliminates boundaries between races and brings us closer together.

Janet Tang Man-wai, 17

SKH Bishop Mok Sau Tseng Secondary School

The light bulb. Without it we would struggle to do anything at night, like study for a test.