A volunteer at a church student-care centre lured a 10-year-old boy to a toilet at the place of worship last July and committed an indecent act on the child.
The full-time national serviceman (NSF), 20, was sentenced yesterday to 18 months' probation and ordered to perform 130 hours of community service.
His parents were bonded for $5,000 to ensure his good behaviour and he must remain indoors from 10pm to 6am every day.
He also has to undergo psychological treatment to address his sexual offending behaviour.
The man pleaded guilty in March to an offence under the Children and Young Persons Act.
A similar charge involving a nine-year-old boy, whom he preyed on in March last year, was considered during sentencing.
The man cannot be named because of a gag order to protect his victims' identities.
He had volunteered at the church located in the east and was assigned to teach children from Primary 1 to 4.
Deputy Public Prosecutor Gregory Gan told District Judge May Mesenas that the offender got to know the 10-year-old boy in January 2017, and they began chatting on Instagram.
The DPP added: "A close relationship developed between the victim and the accused, where the victim regarded the accused as his sibling."
The man also asked the boy to address him as "kor kor", or elder brother in Cantonese.
The court heard that some time last year, the man developed a "curiosity about young boys".
Last July, he told the boy to follow him to a male toilet on the second storey of the church.
He then groped the boy's private parts in one of the cubicles.
The boy later told his mother what the man did and the care services director made a police report on Sept 7 last year.
First-time offenders convicted of committing an indecent act on a child can be jailed for up to five years and fined up to $10,000.
Repeat offenders can be jailed for up to seven years and fined up to $20,000.