Parents who send their children for tuition classes at the Curious Thoughts Academy in Waterloo Street are paying not only for their children to study there but for others too.
The tuition centre, whose goal is to teach a child from a less privileged background for free for every three paying students, now has about 10 paying students, and reaches out to an equal number of beneficiaries.
Ms Lydia Lok, 32, opened the social enterprise in May this year with her husband, Mr Yao Shuohan, 34, and received a $40,000 grant from the Singapore Centre for Social Enterprise for the tuition centre.
Course fees range from $300 per term for eight lessons for pre-schoolers, to up to $460 for upper secondary English lessons. The classes are for children aged between two and 16.
Ms Lok and Mr Yao - who are the two main teachers at the centre - have not drawn a salary yet, ploughing profits back to the centre for rent, to hire teaching assistants and pay for teaching materials.
Ms Lok hopes to reach 65 paying children, allowing them to expand programmes to benefit more needy children.
Some of the beneficiaries join the classes at the centre in Waterloo Street, while others are given free lessons once a week by Ms Lok and Mr Yao who travel to family service centres, children's homes or voluntary welfare organisations.
"We believe that a good grasp of language will be an important leveller for children from less privileged backgrounds, since most other subjects are taught in English," said Ms Lok, who completed a course in teaching phonics with the British Council in 2014.
She previously conducted phonics classes at home and for the Japanese community, and taught at Star Shelter, where she volunteered actively for two years. Mr Yao is a former English teacher who taught at Riverside Secondary.
The couple met at a community service club when they were both students at the National University of Singapore in 2004.
Ms Lok was also a policy officer at the Ministry of Community Development, Youth and Sports, now known as the Ministry of Social and Family Development.
While there, she handled cases related to family violence, including child abuse cases.
Her experience got her thinking that she could help such children by intervening at an earlier stage to help them gain confidence in school, said Ms Lok.
A 38-year-old abuse victim, who cannot be identified, said the centre's pay-it-forward programme has benefited her 11-year-old daughter.
"My daughter told me she wants only Teacher Yao to teach her. She has been improving in her English because Teacher Yao can explain to her clearly," she said.
Financial adviser Briony Guntzenbach, 32, has a two-year-old daughter who attends classes at Curious Thoughts Academy.
"I was initially not aware about the social commitments, but now that I know, I feel it is money well spent. It is good to know that part of every dollar I spend goes to meet the needs of society," she said.