The two Girl Scouts were asked to submit their plans for an "action project" last September.
They wanted to support a children's cause and identified some possibilities online. And when they read about the Children's Cancer Foundation, they knew they had found the perfect one.
"When we learned how many children die from cancer each year, we felt so sad," says Olivia, 13.
There are five public hospitals that treat child cancer patients in Hong Kong: Queen Mary, Prince of Wales, Queen Elizabeth, Princess Margaret and Tuen Mun Hospital.
A total of 176 children were newly diagnosed with cancer in 2010, while 44 died from the disease that year. Leukaemia tops the list of cancers that affect children in Hong Kong. Cancer is a terrible disease, but life is especially tough for child sufferers who are ill-prepared for treatment which includes powerful drugs and a long stay in hospital.
"I dread needles, and it hit me to know that needles are a daily part of their lives," says Maude, 12.
The duo had only a vague idea about raising money for charity, so they sought advice from Lisa Acker, their school guidance counsellor. Finally, they decided to organise a "Swim for Good" event and invited their schoolfriends and their families to sponsor swimmers. With the school's help, they raised almost HK$12,000 - far exceeding their original HK$1,000 target. The foundation suggested the girls buy useful things for child cancer patients at the five hospitals, as well those visiting special playrooms at the Respite Care and Rehabilitation Centre in Shek Kip Mei and the Family Service Centre in Wong Tai Sin.
"In the playrooms, children learn crafts and play games, which help to take their minds off all the needles and drugs," says Tammy Loy Sze-wah, the foundation's hospital play co-ordinator.
"Some children also want to make things to give to staff as a token of their appreciation for their care."
Loy suggested the girls buy some of their favourite DVDs, plus five portable players, books and other items. Maude and Olivia were delighted to personally choose 54items for the children.
"We chose what we like," Olivia says. "I think the children will have fun with the things we bought. Knowing I've helped these children makes me feel good."
Maude agrees: "I want the children to know they're not alone - that there're people out there who love them."