This round we asked: If I lived in a black-and-white world, what one thing would I make colour?

Michelle Fasching, 15, Maryknoll Convent School

It would be horrible to live in a black-and-white world. What if I forgot what colours looked like? That would be terribly depressing - just the thought of it actually scares me. So I've been racking my brains to find a way around a colourless world and I think I've come up with a solution.

I would let my laptop keep its colours. Since I have a camera on my laptop, I could use it as a viewfinder and have my black and white world transformed into a colourful one by looking through my screen.

I could also use my laptop to look up photos and videos of absolutely anything on the internet. That way, I'd be able to see everything in full colour. I could live through my computer and appreciate colours again.

Thomas Cheung Chak-wang, 17, Shatin Tsung Tsin Secondary School

A world without colour would be very boring. If I could choose one thing to have in colour, it would be crayons.

Did you draw with crayons when you were a child? I did. Every great painter started with a crayon. Imagination begins there - with that piece of coloured wax. I just hope that those colours on the paper won't eventually go back to black and white, for that would be too frustrating. I would love to create a whole world of colour.

The least innovative answer to this question is a rainbow. I didn't choose it because, even though a rainbow is fascinating, it disappears within minutes.

Could a rainbow last forever? Yes! But it would have to be drawn with crayons by a child. You could frame the drawing on your wall.

With crayons, you can draw anything - all in dazzling colours.

Lexie Lee Hoi-ching, 16, Hioe Tjo Yoeng College

It would be impossible to live in a black-and-white world. It would be like an eternal winter - still, gloomy and lifeless. If I could make just one thing colour, it would have to be something that gave the world more vitality. For that reason, I would make it paint.

Now, paint itself is nothing remarkable, but it's influential. We could colour the world with it. We could scribble with it on windows and walls. We could fill the world with cartoons and graffiti. We might even paint things on people's clothes or faces, like face art at the Carnival of Venice.

That way, the world would soon sparkle with lively colours. It would bring cheer to people living in a dull world.

Living in a world without colour, people would be unhappy. But some colourful pictures could make them smile, or even laugh.

The paint may not last long. The pictures might fade. But I hope the smiles inspired by the pictures would make people a little happier.

Ice Chan, 13, St Rose of Lima's College

Colours - they are so meaningful in so many ways. If I could choose to make one thing colour in a black-and-white world, then surely it would have to be a Rainbow.

When I say "Rainbow", I like to think the arch of light we see sometimes after rain is a female - a symbol of our dreams and hopes, and world peace. She doesn't visit us often, but when she does, she is dressed so beautifully in seven colours. She stands so high in the sky, bringing people much happiness and a sense of wonder.

People have always attached great significance to Rainbow's colours. Red, for instance, is the symbol of confidence; blue is said to be calming; green is refreshing. And purple is associated with wealth and power, or royalty.

Rainbow, with her seven colours, could help unite people in different parts of the world. Surely we all have the same dream of a beautiful and peaceful world that lasts forever.

Vanessa Sin, 15, St Paul's Convent School

Imagine receiving some heart-breaking news. You feel hopeless, lost, doomed. But then someone steps into the picture and gives you a radiant, brilliant and warm smile. The ice in your heart melts instantly, the wall surrounding you collapses, and brightness embraces you ...

If there is one thing that deserves colour in a cold world of black and white, then it would have to be a smiling face. I would give them the colour of a rainbow. Smiles are infectious; they inspire people. Everyone can smile anytime, anywhere. It is not restricted to any race, religion or gender - it is the sincerity of the smile that counts.

We have all experienced times when a single, well-meant smile saved us from depression and devastation, and to rob people of such a beautiful thing is simply inhumane. May smiles save people from the darkness, just as a spot of colour instantly lightens up a black-and-white world.