Armed with just the basics in the Squeak programming language, as well as encouragement – but no help – from mum and dad, the Chan sisters came up with an application called Health Fairies.

It is an interactive, educational story with an anti-smoking message: The main protaganist is a beautiful young girl who loses her youth, and good looks, because she puffs away like there’s no tomorrow.

The sisters took the bulk of the June holidays to complete their entry. They had to come up with the storyline, draw the characters, and write programs that animated the characters, among other things.

Their effort paid off: Health Fairies landed a merit award in the junior category of the contest, beating 68 other contestants, mostly 11 and 12 year olds.