It's not hard to make life better through invention. Observe carefully, plan, then apply theories to build a practical solution.
This is what students from more than 100 primary and secondary schools did, some of them winning prizes for their unique inventions.
The Third Hong Kong Youth Science and Technology Invention Contest organised by the Hong Kong New Generation Cultural Association received 531 student projects this year, four times as many entries as last year.
Apart from inventions, other categories included scientific dissertations, two new science drawing competitions, and creative proposals.
The contest attracted 119 local primary and secondary schools.
Hearing a crying baby one day, Alvin Chang, 13, had an idea to design a 'nappy alarm' which would alert a pager carried by the mother when urine wet an electric sensor in the nappy.
'The hard part was finding the right metal for the electronic circuit,' said Alvin, champion of the secondary section.